Method for manufacturing multilayer circuit board and resin base material

ABSTRACT

A curable resin composition layer ( 3 ) containing an insulating resin and a curing agent is formed on the surface of an inner layer board having an electrical insulating layer ( 1 ) with a conductor circuit ( 2 ) formed on the surface, so as to cover said conductor circuit. A compound ( 4 ) having a structure capable of coordinating to metal atoms or metal ions is brought into contact with the surface of the curable resin composition layer. An electrical insulating layer ( 7 ) is formed by curing the curable resin composition layer. A metallic thin film layer ( 8 ) is formed on the surface of the electrical insulating layer. A conductor circuit ( 9 ) is formed on the surface of the electrical insulating layer utilizing the metallic thin film layer. A multilayer circuit board is manufactured through these steps.

TECHNICAL FIELD

The present invention relates to a method for manufacturing multilayercircuit boards, and more particularly to a method for manufacturingmultilayer circuit boards excellent in adhesion of conductor patterns(circuits) to electrical insulating layers. The present inventionfurther relates to a method for manufacturing resin base materials onwhich metallic patterns or metallic thin films are formed, suitable formanufacturing multilayer circuit boards and the like.

BACKGROUND ART

As electronic equipment becomes further miniaturized andmultifunctional, higher density has been requested also for the circuitboards used in the electronic equipment. For making the density of thecircuit boards higher, the circuit boards are generally multilayered.The multilayer circuit board is typically obtained by laminating anelectrical insulating layer on the surface of an inner layer board onwhich conductor circuits (conductor patterns) are formed on theoutermost surface thereof and forming a conductor circuit on theelectrical insulating layer, and it is also possible to further laminatea number of electrical insulating layers and conductor circuits asnecessary. Multilayer circuit boards such as multilayer printed wiringboards typically have three or more “conductor patterns/electricalinsulating layers”, and there are known those with more than 70 layersamong them.

In the multilayer circuit boards, adhesion between the electricalinsulating layers and the conductor patterns (circuits) formed thereon(hereinafter abbreviated as “pattern adhesion”) has become important inorder to enhance durability and ensure long life. Generally, theelectrical insulation layers to make multilayers are formed usingelectrical insulating resins.

As the method for enhancing the pattern adhesion, a method in which thesurface of the electrical insulating layer is roughened and thenconductor patterns are formed thereon is widely adopted, as disclosed inJapanese Patent Laid-Open No. 11-23649, Japanese Patent Laid-Open No.11-286562, and Japanese Patent No. 2877110. In order to further improvethe pattern adhesion, a method for coating adhesives for electrolessplating containing polymer components such as rubber or resins on theroughened electrical insulating layers (Japanese Patent Laid-Open No.2001-192844, Japanese Patent Laid-Open No. 2001-123137, and JapanesePatent Laid-Open No. 11-4069) is proposed.

However, some treatment after forming the electrical insulating layerscannot provide sufficient pattern adhesion for a long period of timewhen temperature or humidity changes, and causes delamination to shortenthe life of the circuit boards.

Japanese Patent Laid-Open No. 2001-160689 proposes a method in which theadhesion between an inner layer board and an electrical insulating layerformed thereon is improved by laminating a thiol compound layer on theinner layer board comprising an electrical insulating layer and aconductor circuit formed thereon so as to cover the conductor circuit,and by forming thereon an electrical insulating layer containing ancycloaliphatic olefin polymer.

According to the method disclosed in Japanese Patent Laid-Open No.2001-160689, the adhesion between the inner layer board and theelectrical insulating layer formed thereon can be improved and thedelamination can be suppressed, but the adhesion at the interfacebetween the electrical insulating layer and the conductor circuit formedthereon is insufficient.

Therefore, in multilayer circuit boards, the development of newtechnology is required for improving the adhesion at the interfacebetween an electrical insulating layer formed on an inner layer board tomake multilayers and a conductor circuit formed on the electricalinsulating layer.

On the other hand, the members comprised of resin base materials withmetallic microlines (metallic patterns or conductor patterns) formed onthe surface are used for semiconductor devices, semiconductor devicemounting components, various panel displays, IC cards, optical devicesand the like.

Typically, these metallic patterns are formed by plating. The methodsfor forming metallic patterns by plating include (1) a method forforming a metallic pattern by applying electroless plating on the wholesurface of a resin base material, forming a resist pattern thereon usinga plating resist, growing a metallic layer by electrolytic plating viathe resist pattern, and removing an unnecessary electroless plating partby etching (semi-additive process), and (2) a method for plating adesired pattern by electroless plating on a resin base material to forma metallic pattern and growing an electroplated metal thereon asnecessary (fully-additive process).

The latter method using a pattern plating process is excellent inproductivity, in that metal corrosion by the chemicals used for removingthe unnecessary electroless plating part does not occur and a step forremoving the electroless plating is not required.

In the pattern plating, metallic patterns can be easily obtained byforming an initiator pattern (also referred to as an electroless platingfilm) comprised of a plating-inducing substance on the surface of theresin base material and plating on this pattern (e.g., Japanese PatentLaid-Open No. 7-263841). A large number of investigations have beencarried out on the plating-inducing substances for the purpose ofimproving the adhesion to resin base materials and pattern shapes. Theplating-inducing substances which are proposed include a conductivematerial comprised of a mixture of a conductive polymer or a precursorthereof with water or a polar solvent (Japanese Patent Laid-Open No.2002-26014), a composition consisting of a soluble palladium salt, awater-soluble solvent and water (Japanese Patent Laid-Open No. 7-131135and Japanese Patent Laid-Open No. 7-245467), and a material containing aphotosensitive palladium polymer chelate compound (Japanese PatentLaid-Open No. 2000-147762).

Further, Japanese Patent Laid-Open No. 11-350149 includes resincompositions such as (1) a low molecular weight compound having an N—Hbond, an adhesive polymer having a C═C double bond, and a polybasic acidhaving a C═C double bond, (2) an adhesive polymer having a high N—H bonddensity, and a low molecular weight polybasic acid or a monobasic acidhaving a C═C double bond compatible therewith, (3) a resin componentforming an N—H bond in a curing reaction and a polybasic acid having aC═C double bond, and (4) a resin component forming an N—H bond in acuring reaction and an adhesive polymer having a C═C double bond on amain chain and a polybasic acid having a C═C double bond.

These plating-inducing substances can ensure easy formation of metallicpatterns on resin base materials. However, in the actual use of theresin base materials, the improvement of the adhesion between metallicpatterns and resin base materials has been important problems.

In order to improve the adhesion, the surface of the resin basematerials is generally roughened by a physical or chemical method so asto obtain a surface roughness Ra of several μm. However, roughness ofthe surface by roughening reduces the accuracy of metallic patterns, andmay cause noise in electrical signals in the case of circuit boards.

Therefore, there is desired the development of a method for obtaininghigh adhesion between resin base materials and metallic patterns withoutroughening the surface of the resin base materials.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a method formanufacturing multilayer circuit boards excellent in adhesion ofconductor circuits to electrical insulating layers.

Another object of the present invention is to provide a method formanufacturing resin base materials on which metallic patterns or metalthin films are formed, suitable for manufacturing multilayer circuitboards.

The inventors have diligently studied to achieve the objects describedabove and have hit upon a method for forming a curable resin compositionlayer containing an insulating resin and a curing agent on the surfaceof an inner layer board with a conductor circuit formed on the surface,so as to cover the conductor circuit, and then bringing the surface ofthe curable resin composition layer into contact with a compound havinga structure capable of coordinating to metal atoms or metal ions.

When the curable resin composition layer is cured to form an electricalinsulating layer and a metallic thin film layer is formed on the surfacethereof by electroless plating or sputtering, the adhesion between theelectrical insulating layer and the metallic thin film layer isremarkably improved. Therefore, when a conductive circuit is formed onthe surface of the electric insulating layer according to a conventionalprocess such as a semi-additive process utilizing the metallic thin filmlayer, it is possible to obtain a multilayer circuit board havingexcellent adhesion between an electrical insulating layer and aconductor circuit formed thereon. The same method as the above can beapplied to a method of forming a metallic thin film on a resin basematerial.

Further, when the surface of a resin base material formed from a curableresin composition containing an insulating resin and a curing agent isbrought into contact with a compound having a structure capable ofcoordinating to metal atoms or metal ions in a pattern form and theresin base material is then cured and further subjected to electrolessplating, it is possible to deposit metal on the pattern of the compoundhaving a structure capable of coordination on the surface of the resinbase material. Thus obtained resin base material on which a metallicpattern is formed has excellent adhesion at the interface between theresin base material and the metallic pattern.

The present invention has been completed based on these findings.

Thus, the present invention provides a method for manufacturing amultilayer circuit board comprising:

-   1) step 1 of forming a curable resin composition layer containing an    insulating resin and a curing agent on the surface of an inner layer    board having an electrical insulating layer (a) with a conductor    circuit (A) formed on the surface thereof, so as to cover said    conductor circuit (A);-   2) step 2 of bringing a compound having a structure capable of    coordinating to metal atoms or metal ions into contact with the    surface of said curable resin composition layer;-   3) step 3 of forming an electrical insulating layer (b) by curing    said curable resin composition layer;-   4) step 4 of forming a metallic thin film layer on the surface of    said electrical insulating layer (b); and-   5) step 5 of forming a conductor circuit (B) on the surface of said    electrical insulating layer (b) utilizing said metallic thin film    layer.

In addition, the present invention provides a method for manufacturing aresin base material on which a metallic pattern is formed comprising:

-   I) step (I) of bringing a compound having a structure capable of    coordinating to metal atoms or metal ions into contact in a pattern    form with the surface of a resin base material formed from a curable    resin composition containing an insulating resin and a curing agent;-   II) step (II) of curing said resin base material; and-   III) step (III) of performing electroless plating to deposit metal    on the pattern of a compound having a structure capable of    coordination on the surface of said resin base material.

Furthermore, the present invention provides a method for manufacturing aresin base material on which a metallic thin film is formed comprising:

-   i) step (i) of bringing a compound having a structure capable of    coordinating to metal atoms or metal ions into contact with the    surface of a resin base material formed from a curable resin    composition containing an insulating resin and a curing agent;-   ii) step (ii) of curing said resin base material; and-   iii) step (iii) of performing electroless plating or sputtering to    form a metallic thin film on the surface of said resin base    material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an example of an inner layer board for usein the present invention;

FIG. 2 is a sectional view showing an example of a step of forming acurable resin composition layer on the surface of an inner layer boardso as to cover a conductor circuit;

FIG. 3 is a sectional view showing an example of a step of bringing acompound having a structure capable of coordinating to metal atoms ormetal ions into contact with the surface of a curable resin compositionlayer;

FIG. 4 is a sectional view showing an example of a state of penetrationof a compound having a structure capable of coordination after the abovedescribed contact treatment and a step of forming via holes;

FIG. 5 is a sectional view showing an example of a step of forming ametallic thin film layer; and

FIG. 6 is a sectional view showing an example of a step of forming aconductive circuit on the surface of an electrical insulating layerutilizing a metallic thin film layer.

BEST MODE FOR CARRYING OUT THE INVENTION

1. A General Outline of a Method for Manufacturing a Multilayer CircuitBoard

The method for manufacturing the multilayer circuit board of the presentinvention has the following five steps.

<Step 1>

On the surface of an inner layer board having an electrical insulatinglayer (a) with a conductor circuit (A) formed on the surface thereof(outer most layer), a curable resin composition layer containing aninsulating resin and a curing agent is formed so as to cover theconductor circuit (A).

In the curable resin composition layer, the curable resin composition ispresent in an uncured or a semi-cured state.

<Step 2>

A compound having a structure capable of coordinating to metal atoms ormetal ions is brought into contact with the surface of the curable resincomposition layer. The methods for bringing the compound into contactwith the surface of the curable resin composition layer includeimmersion of the curable resin composition layer in a solution of theabove described compound, coating of the solution of the above describedcompound on the curable resin composition layer and the like.

When the compound having a structure capable of coordinating to metalatoms or metal ions is brought into contact with the surface of thecurable resin composition layer, the compound is adsorbed on the surfaceof the curable resin composition layer and penetrated into the resincomposition layer, and at least part of the compound is presentpenetrating around the surface of the resin composition layer.

<Step 3>

The curable resin composition layer is cured to form the electricalinsulating layer (b). The curing can generally be performed by heating.The compound having a structure capable of coordinating to metal atomsor metal ions penetrates around the surface of the electrical insulatinglayer (b) and is firmly held.

Before or after the curing, via holes can be formed for the continuitybetween an inner layer conductor circuit and an outer layer conductorcircuit.

<Step 4>

A metallic thin film layer is formed on the surface of the electricalinsulating layer (b). The electrical insulating layer (b) includes thecompound having a structure capable of coordinating to metal atoms ormetal ions adsorbed or penetrated around the surface, so that it isexcellent in the adhesion with the metallic thin film layer withoutroughening the surface.

In addition, as the surface layer is not formed such that the compoundhaving a structure capable of coordinating to metal atoms or metal ionsis separated from the surface, the metallic thin film layer is formeddirectly on surface of the electrical insulating layer (b), and itsadhesion at the interface is remarkably enhanced by the action of thecompound.

The metallic thin film layer can be formed by electroless plating,sputtering or the like. After the step 4, a step of heat-treating themetallic thin film layer is preferably added for enhancing the adhesion.The heat treatment of the metallic thin film layer may be carried outunder pressure.

<Step 5>

A conductor circuit (B) is formed on the surface of the electricalinsulating layer (b) utilizing the metallic thin film layer. The methodfor forming thick conductor patterns (circuits) by electrolytic platingutilizing the metallic thin film layer formed by electroless plating orsputtering as a seed layer is well known in the art.

Each of the above described steps will now be described in detail below.Incidentally, FIGS. 1 through 6 show steps 1 through 5 which are carriedout on both sides using an inner layer board having conductor circuitson both sides, but these steps may only be on one side. Moreover,multilayers of two or more may be made on one or both sides of the innerlayer board. Therefore, the following description should be construed asshowing representative embodiments of the present invention.

2. Step 1

An inner layer board for use in step 1 of the present invention is theinner layer board with a conductor circuit formed on the surface. Aninner layer board has a conductor circuit (A) formed on the surface ofan electrical insulating layer (a). Typically, it has a structure inwhich conductor circuits (A, A′) are formed on both sides of anelectrical insulating layer (a) and is regarded as a core of amultilayer circuit board.

Specific examples of the inner layer board include a printed wiringboard and a silicon wafer substrate. The inner layer board may havevarious structures such as through holes other than conductor circuits.The electrical insulating layer (a) may be a single layer or a laminateprepared by laminating glass cloths (prepregs) impregnated with resins.The inner layer board may be partially laminated.

The inner layer board has a thickness of preferably from 50 μm to 2 mm,more preferably from 60 μm to 1.6 mm, and most preferably from 100 μm to1 mm.

The inner layer board preferably has the conductor circuits (A, A′) 2and 2′ formed on both sides of the electrical insulating layer (a), asshown in FIG. 1. The finished multilayer circuit board that has beenmade as vertically symmetrical as possible can minimize the warpage ofthe board and can reduce the influence of the warpage in the solderingwork.

The electrical insulating layer (a) composing the inner layer board ispreferably formed using a resin composition composed mainly ofinsulating resins having electrical insulating properties. Theinsulating resins may include, for example, but not limited to,cycloaliphaticolefin polymers, epoxy resins, maleimide resins, (meth)acrylic resins, diallyl phthalate resins, triazine resins, aromaticpolyether polymers, cyanate ester polymers, and polyimide resins.Conventionally, a curable resin composition containing any of theseinsulating resins and a curing agent is used to form a resin basematerial, which is cured to prepare the electrical insulating layer (a).The inner layer board may contain glass fibers or resin fibers forimproving strength. The material of the conductor circuit layer (A) forcomposing the inner layer board is typically a conductive metal.

On the surface of the inner layer board, a curing resin compositionlayer containing an insulating resin and a curing agent is formed so asto cover the conductor circuit (A). When the curable resin compositionlayers are formed on both sides of the inner layer board, curable resincomposition layers 3 and 3′ are formed on both sides of the electricalinsulating layer (a) 1 of the inner layer board so as to cover conductorcircuits (A, A′) 2 and 2′, as shown in FIG. 2.

The curable resin composition is present in an uncured or a semi-curedstate in the curable resin composition layer. The curable resincomposition layer that is uncured means that substantially whole of theresin composition layer can be dissolved in a solvent in which theinsulating resin composing the resin composition layer is soluble.

The curable resin composition layer is sometimes partially cured byvarious thermal histories to which the layer is exposed when it isformed, and is brought into a semi-cured state. The curable resincomposition layer that is semi-cured means the layer that is partiallycured to the extent further curable by heating. Preferably, the curableresin composition layer that is semi-cured is in a state that it can bepartially dissolved in a solvent in which the insulating resin composingthe resin composition layer is soluble, or has a swelling ratio of 200%or more relative to the volume before immersion, when the resincomposition layer is immersed in the solvent for 24 hours.

Methods of forming a thermoset resin composition layer on the surface ofan inner layer board preferably include, but not limited to, a method offorming the resin composition layer by bonding together films (includingsheets) of a curable resin composition containing an insulating polymerand a curing agent so as to be in contact with the conductor circuit onthe inner layer board (method 1), or a method of forming an uncured or asemi-cured resin composition layer by coating a solution of a curableresin composition containing an insulating polymer and a curing agent onthe surface of the inner layer board and drying it (method 2).

Forming the resin composition layer by method 1 is more preferable, inthat the in-plane uniformity of the adhesion with the metallic thin filmlayer formed on the electrical insulating layer obtained by curing acurable resin composition layer is high.

When the resin composition layer is formed by the method 1, the surfaceof an inner layer board on which a conductive circuit is formed ispreferably pre-treated before the films of a curable resin compositionare bonded together in order to improve the adhesive strength betweenthe inner layer board on which a conductive circuit is formed and anelectrical insulating layer. The pre-treatment methods include (1) amethod of bringing an alkaline aqueous solution of sodium chlorite,permanganic acid or the like into contact with the surface of the innerlayer board to roughen the surface, (2) a method of oxidizing thesurface by an alkaline aqueous solution of potassium persulfate, anaqueous solution of potassium sulfide-ammonium chloride or the like andthen reducing it, (3) a method of depositing the plating on the part ofthe conductor circuit on the inner layer board to roughen it, (4) amethod of forming a primer layer on the surface of the inner layer boardby a thiol compound, a silane compound or the like.

Among these treatment methods, a method of forming a primer layer usingthiol compounds such as 2-di-n-butylamino-4,6-dimercapto-s-triazine issuitable in that when the conductor circuit is formed of copper,corrosion of the copper is prevented and high adhesion is obtained.

(1) Insulating Resins:

The insulating resins for composing the curable resin composition arenot limited as long as they have electrical insulating properties, andinclude, as specific examples thereof, epoxy resins, maleimide resins,(meth) acrylic resins, diallyl phthalate resins, triazine resins,cycloaliphatic olefin polymers, aromatic polyether polymers,benzocyclobutene polymers, cyanate ester polymers, and polyimide resins.

Among these insulating resins, cycloaliphatic olefin polymers, aromaticpolyether polymers, benzocyclobutene polymers, cyanate ester polymers,and polyimide resins are preferred; cycloaliphatic olefin polymers andaromatic polyether polymers are more preferred; and cycloaliphaticolefin polymers are most preferred.

Liquid crystal polymers can also be used as the insulating resins.Examples of the liquid crystal polymers may include polymers of aromaticor aliphatic dihydroxy compounds, polymers of aromatic or aliphaticdicarboxylic acids, polymers of aromatic hydroxycarboxylic acids andpolymers of aromatic diamines, aromatic hydroxyamines or aromaticaminocarboxylic acids.

Although there is no particular limit in the weight average molecularweight (Mw) of the insulating resins, it ranges preferably from 10,000to 1,000,000, more preferably from 50,000 to 500,000, when theinsulating resin is an insulating polymer such as a cycloaliphaticolefin polymer. The insulating polymer having a weight average molecularweight of 10,000 to 1,000,000 is desirably present in a ratio ofpreferably 20% or more by weight, more preferably from 30 to 100% byweight relative to 100% by weight of the insulating resin componentcontained in a curable resin composition, in that when electrolessplating is performed to form a metallic thin film layer in later step 4,the roughening of the electrical insulating layer (b) by thepre-treatment is suppressed.

As the insulating resins other than the polymer having a weight averagemolecular weight within the range of 10,000 to 1,000,000, the insulatingresin having a weight average molecular weight of less than the lowerlimit of the range, or the insulating polymer having a weight averagemolecular weight of more than the upper limit of the range can be usedin combination with the above described insulating resin.

In the present invention, the weight average molecular weight is theweight average molecular weight in terms of polystyrene or polyisoprenedetermined by gel permeation chromatography (GPC).

Cycloaliphatic olefin polymers refer to unsaturated hydrocarbon polymershaving a cycloaliphatic structure. The cycloaliphatic structure, whichincludes a cycloalkane structure and a cycloalkene structure, ispreferably a cycloalkane structure in terms of mechanical strengths,heat resistance and the like. The cycloaliphatic structure may be eithermonocyclic or polycyclic (such as fused polycyclic, bridged ring, or acombination thereof). The number of carbon atoms composing thecycloaliphatic structure is, but not limited to, in the range generallyfrom 4 to 30, preferably from 5 to 20 and more preferably from 5 to 15.This highly balances various properties such as mechanical strengths,heat resistance and moldability. The cycloaliphatic olefin polymers foruse in the present invention preferably exhibit thermo setting propertyin combination with curing agents.

Cycloaliphatic olefin polymers preferably have polar groups. The polargroups may include a hydroxyl group, a carboxyl group, an alkoxy group,an epoxy group, a glycidyl group, an oxycarbonyl group, a carbonylgroup, an amino group, an ester group, and a carboxylic anhydride group.A carboxyl group and a carboxylic anhydride group are preferred amongthem.

Cycloaliphatic olefin polymers may be obtained, typically, by (1) amethod for subjecting cycloaliphatic olefins to addition polymerizationor ring-opening polymerization and hydrolyzing the unsaturated bondportions of the resultant polymers as necessary, or by (2) a method forsubjecting aromatic olefins to addition polymerization and hydrolyzingthe aromatic ring portions of the resultant polymers.

The cycloaliphatic olefin polymers having polar groups may be obtainedby, for example, (1) a method for introducing polar groups intocycloaliphatic olefin polymers by modification reaction, (2) a methodfor copolymerizing monomers including polar groups as copolymerizationcomponents, or (3) a method for copolymerizing monomers including polargroups such as an ester group as copolymerization components and thenhydrolyzing the ester group or the like.

Examples of cycloaliphatic olefins that are used for obtainingcycloaliphatic olefin polymers include: norbornene monomers such asbicyclo[2.2.1]-hept-2-ene (trivial name “norbornene”),5-methyl-bicyclo[2.2.1]-hept-2-ene,5,5-dimethyl-bicyclo[2.2.1]-hept-2-ene,5-ethyl-bicyclo[2.2.1]-hept-2-ene, 5-butyl-bicyclo[2.2.1]-hept-2-ene,5-hexyl-bicyclo[2.2.1]-hept-2-ene, 5-octyl-bicyclo[2.2.1]-hept-2-ene,5-octadecyl-bicyclo[2.2.1]-hept-2-ene,5-ethylidene-bicyclo[2.2.1]-hept-2-ene,5-methylidene-bicyclo[2.2.1]-hept-2-ene,5-vinyl-bicyclo[2.2.1]-hept-2-ene, 5-propenyl-bicyclo[2.2.1]-hept-2-ene,5-methoxy-carbonyl-bicyclo[2.2.1]-hept-2-ene,5-cyano-bicyclo[2.2.1]-hept-2-ene,5-methyl-5-methoxycarbonyl-bicyclo[2.2.1]-hept-2-ene,5-ethoxycarbonyl-bicyclo[2.2.1]-hept-2-ene,bicyclo[2.2.1]-hept-5-enyl-2-methyl propionate,bicyclo[2.2.1]-hept-5-enyl-2-methyl octanate,bicyclo[2.2.1]-hept-2-ene-5,6-dicarboxylic anhydride,5-hydroxymethylbicyclo[2.2.1]-hept-2-ene,5,6-di(hydroxymethyl)-bicyclo[2.2.1]-hept-2-ene,5-hydroxy-i-propylbicyclo[2.2.1]-hept-2-ene,5,6-dicarboxy-bicyclo[2.2.1]-hept-2-ene,bicyclo[2.2.1]-hept-2-ene-5,6-dicarboxylic imide,5-cyclopentyl-bicyclo[2.2.1]-hept-2-ene,5-cyclohexyl-bicyclo[2.2.1]-hept-2-ene,5-cyclohexenyl-bicyclo[2.2.1]-hept-2-ene,5-phenyl-bicyclo[2.2.1]-hept-2-ene,tricyclo[4.3.0.1^(2,5)]deca-3,7-diene (trivial name“dicyclopentadiene”), tricyclo[4.3.0.1^(2,5) ]deca-3-ene,tricyclo[4.4.0.1^(2,5)]undeca-3,7-diene,tricyclo[4.4.0.1^(2,5)]undeca-3,8-diene,tricyclo[4.4.0.1^(2,5)]undeca-3-ene,tetracyclo[7.4.0.1^(10,13).0^(2,7)]-trideca-2,4,6-11-tetraene (aliasname “1,4-methano-1,4,4a,9a-tetrahydrofluorene”),tetracyclo[8.4.0.1^(11,14).0^(3,8)]-tetradeca-3,5,7,12,11-tetraen e(alias name “1,4-methano-1,4,4a,5,10,10a-hexahydroanthracene”),tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene (trivial name“tetracyclododecene”),8-methyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-ethyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-methylidene-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-ethylidene-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-vinyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-propenyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-methoxycarbonyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-methyl-8-methoxycarbonyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-hydroxymethyl-tetracyclo[4.4.0.1^(2,5).1^(2,5).1^(7,10)]-dodeca-3-ene,8-carboxy-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-cyclopentyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-cyclohexyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-cyclohexenyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene,8-phenyl-tetracyclo[4.4.0.1^(2,5)1^(7,10)]-dodeca-3-ene, andpentacyclo[6.5.1.1^(3,6).0^(2,7).0^(9,13)]pentadeca-3,10-diene,pentacyclo[7.4.0.1^(3,6).1^(10,13).0^(2,7)]-pentadeca-4,11-diene;monocyclic cycloalkenes such as cyclobutene, cyclopentene, cyclohexene,3,4-dimethylcyclopentene, 3-methylcyclohexene,2-(2-methylbutyl)-1-cyclohexene, cyclooctene,3a,5,6,7a-tetrahydro-4,7-methano-1H-indene, and cycloheptene; vinylalicyclic hydrocarbon monomers such as vinylcyclohexene andvinylcyclohexane; and alicyclic conjugated diene monomers such ascyclopentadiene and cyclohexadiene.

Examples of aromatic olefins include styrene, α-methylstyrene, anddivinylbenzene.

Cycloaliphatic olefins and/or aromatic olefins may be used singly or incombination.

Cycloaliphatic olefin polymers may include those obtained bycopolymerizing cycloaliphatic olefins and/or aromatic olefins withmonomers copolymerizable therewith.

Examples of monomers that are copolymerizable with a cycloaliphaticolefin or an aromatic olefin include: ethylene; α-olefins having 3 to 20carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene,3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene,4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene,4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene,1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and1-eicosene; unconjugated dienes such as 1,4-hexadiene,4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, and 1,7-octadiene. Thesemonomers may be used singly or in combination.

A method for polymerizing cycloaliphatic olefins and aromatic olefinsand a method of hydrogenation performed as necessary are notparticularly limited, but may be performed in accordance with well-knownmethods.

Examples of the cycloaliphatic olefin polymers include (1) ring-openingpolymers of norbornene monomers and their hydrogenated derivatives, (2)addition polymers of norbornene monomers, (3) addition polymers ofnorbornene monomers to vinyl compounds, (4) monocyclic cycloalkenepolymers, (5) cycloaliphatic conjugated diene polymers, (6) vinylcycloaliphatic hydrocarbon polymers and their hydrogenated derivatives,and (7) aromatic ring hydrogenated derivatives of aromatic olefinpolymers. Among them, ring-opening polymers of norbornene monomers andtheir hydrogenated derivatives, addition polymers of norbornenemonomers, addition polymers of norbornene monomers to vinyl compounds,and aromatic ring hydrogenated derivatives of aromatic olefin polymersare preferred, and hydrogenated derivatives of ring-opening polymers ofnorbornene monomers are most preferred.

The cycloaliphatic olefin polymers may be used singly or in combination.

Among the cycloaliphatic olefin polymers, most preferred ring-openingpolymers of norbornene monomers and their hydrogenated derivatives areclassified as the different polymers from the polyolefin resins obtainedby copolymerizing olefins represented by C_(n)H_(2n) due to thedifference of their structures.

The methods for adjusting the weight average molecular weight of thecycloaliphatic olefin polymers may be performed according toconventional methods, and include, for example, a method in which whenundergoing the ring-opening polymerization of cycloaliphatic olefinsusing a titanium-based or tungsten-based catalyst, a molecular weightmodifier such as vinyl compounds or diene compounds is added in anamount approximately from 0.1 to 10 mol % relative to the total amountof the monomers. At this time, the use of smaller amount of themolecular weight modifier will provide polymers having relatively highweight average molecular weight, and larger amount will provide polymershaving relatively low weight average molecular weight.

Examples of vinyl compounds that are used as a molecular weight modifierinclude: α-olefin compounds such as 1-butene, 1-pentene, 1-hexene, and1-octene; styrene compounds such as styrene and vinyl toluene; ethercompounds such as ethyl vinyl ether, isobutyl vinyl ether, and allylglycidyl ether; halogen containing vinyl compounds such as allylchloride; oxygen containing vinyl compounds such as allyl acetate, allylalcohol, and glycidyl methacrylate; nitrogen containing vinyl compoundssuch as acrylamide.

Examples of diene compounds that are used as a molecular weight modifierinclude: unconjugated diene compounds such as 1,4-pentadiene,1,5-hexadiene, 1,6-heptadiene, 2-methyl-1,4-pentadiene, and2,5-dimethyl-1,5-hexadiene; and conjugated diene compounds such as1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene,1,3-pentadiene, and 1,3-hexadiene.

The glass transition temperature of the cycloaliphatic olefin polymersmay be appropriately selected depending on intended use, and isgenerally 50° C. or higher, preferably 70° C. or higher, more preferably100° C. or higher, most preferably 125° C. or higher.

(2) Curing Agent

Curing agents for use in the present invention include, but not limitedto, for example, ionic curing agents, radical curing agents, and curingagents having both ionic and radical properties. Examples of curingagents include: nitrogen curing agents such as isocyanurate curingagents that contain an allyl group and an epoxy group and do not containa halogen such as 1-allyl-3,5-diglycidylisocyanurate and1,3-diallyl-5-glycidylisocyanurate; polyhydric epoxy compounds such asglycidylether expoxy compounds such as bisphenol Abis(ethyleneglycolglycidylether)ether, bisphenol Abis(diethyleneglycolglycidylether)ether, bisphenol Abis(triethyleneglycolglycidylether)ether, and bisphenol Abis(propyleneglycolglycidylether)ether, cycloaliphatic epoxy compounds,and glycidyl ester epoxy compounds; dicarboxylic acid derivatives suchas acid anhydrides and dicarboxylic acid compounds; and polyol compoundssuch as diol compounds, triol compounds, and polyhydric phenolcompounds.

Among these curing agents, polyhydric epoxy compounds are preferred, andglycidyl ether epoxy compounds are particularly preferred in terms ofenhancing crack resistance.

(3) Curing Accelerators and Curing Aids

To promote curing reaction between cycloaliphatic olefin polymers andcuring agents, curing accelerators and curing aids may be used. When forexample polyhydric epoxy compounds are used as curing agents, tertiaryamine compounds and trifluorinated boron complex compounds are suitableas curing accelerators. Among them, use of tertiary amine compoundsimproves lamination properties, insulating resistance, heat resistanceand chemical resistance to microscopic wiring (microscopic conductorpattern).

Examples of tertiary amine compounds include acyclic tertiary aminecompounds such as benzyldimethylamine, triethanolamine, triethylamine,tributylamine, tribenzylamine, dimethylformamide; compounds such aspyrazoles, pyridines, pyrazines, pirimidines, indazoles, quinolines,isoquinolines, imidazoles, triazoles and the like. Among them,imidazoles are preferred, and substituted imidazoles having substitutedgroups are most preferred.

Specific examples of substituted imidazole compounds include:alkyl-substituted imidazole compounds such as 2-ethylimidazole,2-ethyl-4-methylimidazole, bis-2-ethyl-4-methylimidazole,1-methyl-2-ethylimidazole, 2-isopropylimidazole, 2,4-dimethylimidazole,and 2-heptadecylimidazole; imidazole compounds substituted by ahydrocarbon group containing a cyclic structure such as an aryl group oraralkyl group such as 2-phenylimidazole, 2-phenyl-4-methylimidazole,1-benzyl-2-methylimidazole, 1-benzyl-2-ethylimidazole,1-benzyl-2-phenylimidazole, benzimidazole,2-ethyl-4-methyl-1-(2′-cyanoethyl)imidazole, and2-ethyl-4-methyl-1-[2′-(3″,5″-diaminotriazinyl)ethyl]imid azole. Amongthem, imidazoles having substituted groups including a ring structureare preferred in terms of compatibility with cycloaliphatic olefinpolymers, and 1-benzyl-2-phenylimidazole is most preferred.

Curing accelerators are used singly or in combination. The loading ofthe curing accelerators is appropriately selected depending on intendeduse, and generally from 0.001 to 30 parts by weight, preferably from0.01 to 10 parts by weight, more preferably from 0.03 to 5 parts byweight, relative to 100 parts by weight of insulating polymers.

Examples of curing aids include oxime-nitroso curing aids such asquinone dioxime, benzoquinone dioxime, and p-nitrosophenol; maleimidecuring aids such as N,N-m-phenylene bismaleimide; allyl curing aids suchas diallyl phthalate, triallyl cyanurate, and triallyl isocyanurate;methacrylate curing aids such as ethylene glycol dimethacrylate andtrimethylol propane trimethacrylate; vinyl curing aids such as vinyltoluene, ethyl vinyl benzene, and divinyl benzene; and tertiary aminecompounds such as 1-benzyl-2-phenylimidazole. In addition to thesecompounds, peroxides acting as curing aids for curing agents having anallyl group can be used.

(4) Other Components

The curable resin composition according to the present invention mayformulate other components as necessary. For example, it is possible toformulate compounds having absorption in the wavelength region of laserbeams used for forming holes such as via holes or through holes. Forexample, silica is used when using carbon dioxide gas laser, andultraviolet absorbers are used when using ultraviolet laser (forexample, UV-YAG laser or the like). Use of compounds having absorptionin the wavelength region of laser beams facilitates the formation ofholes by lasers and reduces the occurrence of a smear.

Specific examples of ultraviolet absorbers include salicylic acidcompounds such as phenyl salicylate, p-tert-butylphenyl salicylate,p-octylphenyl salicylate; benzophenone compounds such as2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone,2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone,2,2′-dihydroxy-4-methoxybenzophenone,2,2′-dihydroxy-4,4′-dimethoxybenzophenone,2-hydroxy-4-methoxy-5-sulfobenzophenone,bis(2-hydroxy-4-methoxybenzoylphenyl)methane; benzotriazole compoundssuch as 2-(2′-hydroxy-5′-methylphenyl)benzotriazole,2-(2′-hydroxy-5′-tert-butylphenyl)benzotriazole,2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)-5-chlorobenzotri azole,2-(2′-hydroxy-3′,5′-di-tert-amylphenyl)benzotriazole,2-[2′-hydroxy-3′-(3″,4″,5″,6″-tetrahydrophthalimidomethyl)-5′-methylphenyl]benzotriazole,2,2-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol],2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]benzotria zole; benzoatecompounds such as2,4-di-tert-butylphenyl-3′,5′-di-tert-butyl-4′-hydroxyben zoate;cyanoacrylate compounds such as2-ethylhexyl-2-cyano-3,3′-diphenylacrylate,ethyl-2-cyano-3,3′-diphenylacrylate; hindered amine compounds such asbis(2,2,6,6-tetramethylpiperidinyl4)sebacate; organic metal compoundssuch as nickel bis(octylphenyl)sulfide,[2,2′-thiobis(4-tert-octylphenolate)]-n-butylamine nickel; and inorganiccompounds such as zinc oxide, tin oxide, titanium oxide, calciumcarbonate, silica, and clay. Among them, benzotriazole compounds arepreferable in terms of being excellent in compatibility with ringstructure-containing polymers and stability during thermal curing.

The ultraviolet absorbers are formulated in an amount of generally from0.1 to 30 parts by weight, preferably from 1 to 10 parts by weight,relative to 100 parts by weight of insulating polymers.

Additional components that may be used include flame retardants,flexible polymers, heat stabilizers, weathering stabilizers,antioxidants, leveling agents, antistatic agents, slip agents,antiblocking agents, antifog agents, lubricant, dye, pigment, naturaloil, synthetic oil, wax, emulsion and fillers. The loadings may beappropriately selected within the range where objects of the presentinvention are not impaired.

(5) Films of Curable Resin Compositions

The films (including sheets) of curable resin compositions used forforming a curable resin composition layer are typically formed fromcurable resin compositions by a solution casting process or a meltcasting process. When the films are formed by the solution castingprocess, a solution of insulating resins and curing agents in organicsolvents (varnish) is coated on supports and then the organic solventsare removed by drying.

The supports for use in the solution casting process include resin films(carrier films) and metal foil. Thermoplastic resin films are generallyused as the resin films, and specifically include polyethyleneterephthalate films, polypropylene films, polyethylene films,polycarbonate films, polyethylene naphthalate films, polyallylate filmsand nylon films. Among these resin films, polyethylene terephthalatefilms and polyethylene naphthalate films are preferred in terms of heatresistance, chemical resistance and peeling properties after lamination.

The metal foil for the supports includes, for example, copper foil,aluminum foil, nickel foil, chromium foil, gold foil and silver foil.Copper foil, particularly electrolytic copper foil or rolled copperfoil, is preferred in terms of good electrical conductance and low cost.The thickness of the supports is, but not particularly limited to,generally from 1 to 150 μm, preferably from 2 to 100 μm, more preferablyfrom 3 to 50 μm, in terms of workability or the like.

The method for obtaining the varnish is not particularly limited, and itcan be obtained, for example, by mixing each component composing thecurable resin composition with an organic solvent. The method for mixingeach component may be in accordance with conventional methods, and mayinclude, for example, methods using agitation with a stirrer and amagnetic stirrer, a high speed homogenizer, a dispersion, a planetarystirring machine, a double spindle stirrer, a ball mill and atriple-roll. The temperature for mixing them is preferably within thetemperature where the reaction by the curing agents has no effect onworkability, and preferably below the boiling point of the organicsolvents to be used at the mixing, in terms of safety.

The organic solvents include, for example, aromatic hydrocarbon organicsolvents such as toluene, xylene, ethylbenzene and trimethylbenzene;aliphatic hydrocarbon organic solvents such as n-pentane, n-hexane andn-heptane; cycloaliphatic hydrocarbon organic solvents such ascyclopentane and cyclohexane; halogenated hydrocarbon organic solventssuch as chlorobenzene, dichlorobenzene and trichlorobenzene; ketoneorganic solvents such as methyl ethyl ketone, methyl isobutyl ketone,cyclopentanone and cyclohexanone; and the like. These organic solventsmay be used singly or in combination.

Among these organic solvents, those preferred in terms of having goodburying properties for microscopic wiring and producing no blisters aremixed organic solvents prepared by mixing non-polar organic solventssuch as aromatic hydrocarbon organic solvents and cycloaliphatichydrocarbon organic solvents with polar organic solvents such as ketoneorganic solvents. The mixing ratio of non-polar organic solvents andpolar organic solvents may be appropriately selected, and rangesgenerally from 5:95 to 95:5, preferably from 10:90 to 90:10, morepreferably from 20:80 to 80:20, by weight ratio.

Usage of organic solvents is appropriately selected depending on objectssuch as thickness control or improvement of flatness, and it rangesgenerally from 5 to 70% by weight, preferably from 10 to 65% by weight,more preferably from 20 to 60% by weight, in terms of solid content ofthe varnish.

Methods for coating include the methods such as dip coating, rollcoating, curtain coating, die coating and slit coating. Conditions forremoving and drying organic solvents are appropriately selecteddepending on types of organic solvents. Drying temperature is generallyfrom 20 to 300° C., preferably from 30 to 200° C. Drying time isgenerally from 30 seconds to 1 hour, preferably from 1 minute to 30minutes.

The thickness of films is generally from 0.1 to 150 μm, preferably from0.5 to 100 μm, more preferably from 1 to 80 μm. When the film is desiredto be obtained by itself, the film is formed on a support and thenpeeled from the support.

For bonding the film of the curable resin composition to the surface ofthe inner layer board in step (1), generally, the film with a support isoverlapped such that the film is brought into contact with the conductorcircuit and subjected to thermo-compression bonding (lamination) using apressure machine such as a pressure laminator, a press, a vacuumlaminator, a vacuum press, or a roll laminator to combine the both sothat substantially no air-gap is present at the interface between theboard surface and the film. The thermo-compression bonding is preferablyperformed under vacuum to improve burying properties to the wiring andto suppress generation of blisters or the like. The temperature duringthe thermo-compression bonding is generally from 30 to 250° C.,preferably from 70 to 200° C.; the strength of the compression bondingis generally from 10 kPa to 20 MPa, preferably from 100 kPa to 10 MPa;and the time of the compression bonding is generally from 30 seconds to5 hours, preferably from 1 minute to 3 hours. During thethermo-compression bonding, the atmosphere is reduced to generally from100 kPa to 1 Pa, preferably from 40 kPa to 10 Pa.

The films to be bonded together to the inner layer board may be two ormore. For example, the inner layer board having a film laminated thereonmay be laminated with a different film, such that it is brought intocontact with the film on the inner layer board, for the purpose ofimproving the flatness of the electrical insulating layer (b) orincreasing the thickness of the electrical insulating layer (b). Whenfilms are laminated by bonding a plurality of films together to theinner layer board, it is the surface of the film laminated last that isbrought into contact with the compound having a structure capable ofcoordinating to metal atoms or metal ions in the next step 2.

When the resin composition layer is formed by a coating process, thevarnish of the curable resin composition may be directly coated on theinner layer board and dried. The procedures and conditions of coatingand drying may be the same as the case for forming the film of thecurable resin composition.

3. Step 2

In step 2, a compound having a structure capable of coordinating tometal atoms or metal ions is brought into contact with the surface ofthe curable resin composition layer formed in step 1. When a film of acurable resin composition is bonded together to an inner layer board toform the resin composition layer, wherein the film has a support, thestep 2 is carried out after the support is removed.

Examples of compounds having a structure capable of coordinating tometal atoms or metal ions (hereinafter may be referred to “acoordination structure-containing compound”) include, but not limitedto, compounds having functional groups capable of coordinating to metalatoms or metal ions such as an amino group, a thiol group, a carboxylgroup or a cyano group; and compounds having unshared electron pairssuch as heterocyclic compounds having coordination capability to metalatoms or metal ions.

Among them, heterocyclic compounds containing nitrogen atoms, oxygenatoms, or sulfur atoms are preferred, and those containing nitrogenatoms are more preferred. These heterocyclic compounds may furthercomprise functional groups capable of coordinating to metal atoms ormetal ions. Heterocyclic compounds further comprising functional groupscapable of coordinating to metal atoms or metal ions are preferable inthat they provide higher pattern adhesion.

Examples of heterocyclic compounds containing an oxygen atom, sulfuratom, or nitrogen atom include pyrroles, pyrrolines, pyrrolidines,pyrazoles, pyrazolines, pyrazolidines, imidazoles, imidazolines,triazoles, tetrazoles, pyridines, piperidines, pyridazines, pyrimidines,pyrazines, piperazines, triazines, tetrazines, indoles, isoindoles,indazoles, purines, norharmanes, perimidines, quinolines, isoquinolines,cinnolines, quinosalines, quinazolines, naphthylidines, pteridines,carbazoles, acridines, phenazines, phenanthridines, phenanthrolines,furans, dioxolanes, pyrans, dioxanes, benzofurans, isobenzofurans,cormalines, dibenzofurans, flavones, trithianes, thiophenes,benzothiophenes, isobenzothiophenes, dithiins, thianthrenes,thienothiophenes, oxazoles, isoxazoles, oxadiazoles, oxazines,morpholines, thiazoles, isothiazoles, thiadiazoles, thiazines, andphenothiazines.

Among them, the following compounds are preferred in that thesecompounds react with the components in a curable resin composition, arefirmly held in the electrical insulating layer (b) to be formed in thenext step, and provide the effect that the metallic thin film layer tobe formed thereafter is hardly delaminated.

(1) Imidazoles:

Imidazoles; imidazoles having a thiol group such as 2-mercaptoimidazole,2-mercaptomethylbenzoimidazole, 2-(2-mercaptoethyl)-benzoimidazole, and2-mercapto-4-azabenzoimidazole; imidazoledithiocarboxylic acids such asimidazole-4-dithiocarboxylic acid, 2-methylimidazole-4-dithiocarboxylicacid, 2-ethylimidazole-4-dithiocarboxylic acid,2-isopropylimidazole-4-dithiocarboxylic acid,2-n-butylimidazole-4-dithiocarboxylic acid,2-phenylimidazole-4-dithiocarboxylic acid,4-methylimidazole-5-dithiocarboxylic acid,2-phenyl-4-methylimidazole-5-dithiocarboxylic acid,2-ethylimidazole-4-dithiocarboxylic acid, and2-n-undecylimidazole-4-dithiocarboxylic acid; imidazoles having acarboxyl group such as imidazole-2-carboxylic acid,imidazole-4-carboxylic acid, 2-methylimidazole-4-carboxylic acid,2-phenylimidazole-4-carboxylic acid,2-methyl-4-methylimidazole-5-carboxylic acid,2-(2-carboxyethyl)-benzoimidazole, and imidazole-2-carboxyamide;imidazoles having an amino group such as1-(2-aminoethyl)-2-methylimidazole, 1-(2-aminoethyl)-2-ethylimidazole,2-aminoimidazole sulfate, and 2-(2-aminoethyl)-benzoimidazole;imidazoles having a cyano group such as 2-cyanioimidazole,4-cyanoimidazole, 4-methyl-5-cyanoimidazole, 2-methyl-5-cyanoimidazole,2-phenyl-5-cyanoimidazole, 4-cyanomethylimidazole,1-(2-cyanoethyl)-2-ethylimidazole,1-(2-cyanoethyl)-2-ethyl-4-methylimidazole,1-(2-cyanoethyl)-2-n-undecylimidazole, and1-(2-cyanoethyl)-2-phenylimidazole; imidazoles having other groups suchas 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole,2-n-propylimidazole, 2-n-butylimidazole, 2-phenylimidazole,2-n-undecylimidazole, 2-n-heptadecylimidazole, 1,2-dimethylimidazole,1-methyl-2-ethylimidazole, 1-benzyl-2-methylimidazole,1-benzyl-2-ethylimidazole, 1-benzyl-2-phenylimidazole,4-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole,2-n-butyl-4-methylimidazole, 2-phenyl-4-methylimidazole,1-methylimidazole, 2-n-butyl-4-chloro-5-formylimidazole,2-formylimidazole, 4-formylimidazole, 2-methyl-4-formylimidazole,2-n-butyl-4-formylimidazole, 2-phenyl-4-formylimidazole,4-methyl-5-formylimidazole, 2-ethyl-4-methyl-5-formylimidazole,2-phenyl-4-methyl-5-formylimidazole, 2-methyl-4,5-diformylimidazole,2-ethyl-4,5-diformylimidazole, 2-isopropyl-4,5-diformylimidazole,2-n-propyl-4,5-diformylimidazole, 2-n-butyl-4,5-diformylimidazole,2-n-undecyl-4,5-diformylimidazole, 2-nitroimidazole,1-{2-hydroxy-3-(3-trimethoxysilylpropyloxy)}propylimidazole,4-hydroxy-methylimidazole hydrochloride, 2-hydroxymethylimidazolehydrochloride, 2-methyl-4,5-dihydroxymethylimidazole,2-ethyl-4,5-dihydroxymethylimidazole,2-isopropyl-4,5-dihydroxymethylimidazole,2-n-propyl-4,5-dihydroxymethyl-imidazole,2-n-butyl-4,5-dihydroxymethylimidazole,2-phenyl-4,5-dihydroxymethylimidazole,2-n-undecyl-4,5-dihydroxymethylimidazole, benzoimidazole,benzoimidazole, 2-hydroxymethylbenzoimidazole,2-chloromethylbenzo-imidazole,1-{3-(3-trimethoxysilylpropyloxy)}-propylimidazole,4-thiocarbamoylimidazole, 2-methyl-4-thiocarbamoylimidazole,4-methyl-5-thiocarbamoylimidazole,2-ethyl-4-methyl-5-thiocarbamoylimidazole,2-phenyl-4-thiocarbamoylimidazole,2-(2′-methylimidazolyl-4′)-benzoimidazole,2-(2′-phenylimidazolyl-4′)-benzoimidazole, 4-azabenzoimidazole,2-hydroxy-4-azabenzoimidazole, and 2-hydroxymethyl-4-azabenzoimidazole;or the like.

(2) Pyrazoles:

Pyrazole; pyrazoles having a carboxyl group such as4-carboxymethylpyrazole, 5-carboxymethylpyrazole,1-methyl-4-carboxymethylpyrazole, 1-isopropyl-4-carboxymethylpyrazole,1-benzyl-4-carboxymethylpyrazole, 1-methyl-5-carboxymethylpyrazole,1-isopropyl-5-carboxymethylpyrazole, 1-benzyl-5-carboxymethylpyrazole,1,3-dimethyl-4-carboxymethylpyrazole,1-isopropyl-3-methyl-4-carboxymethylpyrazole,1-benzyl-3-methyl-4-carboxymethylpyrazole,1,3-dimethyl-5-carboxymethylpyrazole,1-isopropyl-3-methyl-5-carboxymethylpyrazole,1-benzyl-3-methyl-5-carboxymethylpyrazole,1,5-dimethyl-4-carboxymethylpyrazole,1-methyl-4-carboxymethyl-5-hydroxypyrazole,1-methyl-4-chloro-5-carboxymethyl-pyrazole,1-methyl-4,5-dicarboxymethylpyrazole,1-methyl-4-cyano-5-carboxymethylpyrazole,1-methyl-4-carboxymethyl-5-chloropyrazole,1-isopropyl-4-carboxymethyl-5-methylpyrazole,1-isopropyl-4-carboxymethyl-5-hydroxypyrazole,1-isopropyl-4-chloro-5-carboxymethylpyrazole,1-isopropyl-4,5-dicarboxymethylpyrazole,1-isopropyl-4-dicarboxymethyl-5-chloropyrazole,1-benzyl-4-carboxymethyl-5-hydroxypyrazole,1-benzyl-4-carboxymethyl-5-methylpyrazole,1-benzyl-4-chloro-5-carboxymethylpyrazole,1-benzyl-4,5-dicarboxymethylpyrazole,1-benzyl-4-carboxymethyl-5-chloropyrazole,3-methyl-4-carboxymethyl-5-hydroxypyrazole,3,5-dimethyl-4-carboxymethylpyrazole,3-methyl-4-chloro-5-carboxymethylpyrazole,3-methyl-4,5-dicarboxymethylpyrazole,3-methyl-4-dicarboxymethyl-5-chloropyrazole,1,3,5-trimethyl-4-carboxymethylpyrazole,1-benzyl-3,5-dimethyl-4-carboxymethylpyrazole,1,3-dimethyl-4-carboxymethyl-5-hydroxypyrazole,1,3-dimethyl-4-chloro-5-carboxymethylpyrazole, and1,3-dimethyl-4,5-dicarboxymethylpyrazole; pyrazoles having a cyano groupsuch as 4-cyanopyrazole, 1-methyl-4-cyanopyrazole,1-isopropyl-4-cyanopyrazole, 1-benzyl-4-cyanopyrazole,1,3-dimethyl-4-cyanopyrazole, 1-isopropyl-3-methyl-4-cyanopyrazole,1-benzyl-3-methyl-4-cyanopyrazole, 1,5-dimethyl-4-cyanopyrazole,1-isopropyl-4-cyano-5-methylpyrazole,1-isopropyl-4-cyano-5-hydroxypyrazole,1-isopropyl-4-cyano-5-chloropyrazole, 1-benzyl-4-cyano-5-methylpyrazole,1-benzyl-4-cyano-5-hydroxypyrazole, 1-benzyl-4-cyano-5-chloropyrazole,3,5-dimethyl-4-cyanopyrazole, 3-methyl-4-cyano-5-hydroxypyrazole,3-methyl-4-cyano-5-chloropyrazole, 1,3,5-trimethyl-4-cyanopyrazole,1-benzyl-3,5-dimethyl-4-cyanopyrazole,1,3-dimethyl-4-cyano-5-hydroxypyrazole; pyrazoles having an amino groupsuch as 5-aminopyrazole, 1-methyl-5-aminopyrazole,1-isopropyl-5-aminopyrazole, 1-benzyl-5-aminopyrazole,1,3-dimethyl-5-aminopyrazole, 1-isopropyl-3-methyl-5-aminopyrazole,1-benzyl-3-methyl-5-aminopyrazole, 1-methyl-4-chloro-5-aminopyrazole,1-methyl-4-cyano-5-aminopyrazole, 1-isopropyl-4-chloro-5-aminopyrazole,3-methyl-4-chloro-5-aminopyrazole, 1-benzyl-4-chloro-5-aminopyrazole,and 1,3-dimethyl-4-chloro-5-aminopyrazole; pyrazoles having any two ormore amino groups, carboxyl groups, or cyano groups such as1-methyl-4-carboxymethyl-5-aminopyrazole,1-isopropyl-4-carboxymethyl-5-aminopyrazole,1-benzyl-4-carboxymethyl-5-aminopyrazole,3-methyl-4-carboxymethyl-5-aminopyrazole,1,3-dimethyl-4-carboxymethyl-5-aminopyrazole,1-isopropyl-4-cyano-5-aminopyrazole, 1-benzyl-4-cyano-5-aminopyrazole,3-methyl-4-cyano-5-aminopyrazole, 1,3-dimethyl-4-cyano-5-aminopyrazole,1-isopropyl-4-cyano-5-carboxymethylpyrazole,1-benzyl-4-cyano-5-carboxymethylpyrazole,3-methyl-4-cyano-5-carboxymethylpyrazole, and1,3-dimethyl-4-cyano-5-carboxymethylpyrazole; pyrazoles having othergroups such as 1-methylpyrazole, 1-isopropylpyrazole, 1-benzylpyrazole,3-methylpyrazole, 5-methylpyrazole, 1,3-dimethylpyrazole,4-chloropyrazole, 5-hydroxypyrazole, 5-chloropyrazole,1-methyl-4-chloropyrazole, 1-isopropyl-4-chloropyrazole,1,5-dimethylpyrazole, 1-methyl-5-hydroxypyrazole,1-methyl-5-chloropyrazole, 1-isopropyl-5-methylpyrazole,1-isopropyl-5-hydroxypyrazole, 1-isopropyl-5-chloropyrazole,1-benzyl-5-methylpyrazole, 1-benzyl-5-hydroxypyrazole,1-benzyl-5-chloropyrazole, 1,3-dimethyl-4-chloropyrazole,1-benzyl-3-methyl-4-chloropyrazole, 1,3,5-trimethylpyrazole,1,3-dimethyl-5-hydroxypyrazole, 1,3-dimethyl-5-chloropyrazole,1-isopropyl-3-methyl-5-hydroxypyrazole, 1-benzyl-3,5-dimethylpyrazole,1-benzyl-3-methyl-5-ethylpyrazole, 1-methyl-4-cyano-5-hydroxypyrazole,1-methyl-4,5-dichloropyrazole, 1-methyl-4-cyano-5-chlordpyrazole,1-isopropyl-4-chloro-5-methylpyrazole,1-isopropyl-4-chloro-5-hydroxypyrazole,1-isopropyl-4,5-dichloropyrazole, 1-benzyl-4-chloro-5-methylpyrazole,1-benzyl-4-chloro-5-hydroxypyrazole, 1-benzyl-4,5-dichloropyrazole,3,5-dimethyl-4-chloropyrazole, 3-methyl-4-chloro-5-hydroxypyrazole,3-methyl-4,5-dichloropyrazole, 1,3,5-trimethyl-4-chloropyrazole,1-isopropyl-3,5-dimethyl-4-chloropyrazole, and1,3-dimethyl-4-chloro-5-hydroxypyrazole; or the like.

(3) Triazoles:

1,2,4-Triazole; triazoles having an amino group such as1-amino-1,2,4-triazole, 2-amino-1,2,4-triazole,1,2-diamino-1,2,4-triazole, 1-amino-2-hydroxy-1,2,4-triazole,2,5-diamino-1,2,4-triazole, 2-amino-5-hydroxy-1,2,4-triazole,1,2,5-triamino-1,2,4-triazole, and 1,2-diamino-5-hydroxy-1,2,4-triazole;triazoles having a thiol group such as 1-mercapto-1,2,4-triazole and2-mercapto-1,2,4-triazole; triazoles having any two or more aminogroups, thiol groups, or carboxyl groups such as1-amino-2-mercapto-1,2,4-triazole, 1-mercapto-2-amino-1,2,4-triazole,2-amino-5-mercapto-1,2,4-triazole, 1,2-diamino-5-mercaptotriazole,1-mercapto-2,5-diamino-1,2,4-triazole,1-mercapto-2-amino-5-mercapto-1,2,4-triazole,1-mercapto-2-amino-5-hydroxy-1,2,4-triazole,1,5-dimercapto-2-amino-1,2,4-triazole, and3-amino-1,2,4-triazole-5-carboxylic acid; triazoles having other groupssuch as 2-hydroxy-1,2,4-triazole; or the like.

(4) Triazines:

Triazines having an amino group such as 2-aminotriazine,2,4-diaminotriazine, and2,4-diamino-6-[6-[2-(2methyl-1-imidazolyl)ethyl]triazine]; triazineshaving a thiol group such as 2-anilino-4,6-dimercapto-s-triazine,2-morpholyl-4,6-dimercapto-s-triazine,2-monolauryl-4,6-dimercapto-s-triazine, 2,4,6-trimercapto-s-triazine,2,4,6-trimercapto-s-triazine-monosodium salt,2,4,6-trimercapto-s-triazine-trisodium salt; and triazines having anamino group and a thiol group such as2-dibutylamino-4,6-dimercapto-s-triazine; or the like.

Among them, preferred are imidazoles, pyrazoles, triazoles, or triazineshaving an amino group, thiol group, carboxyl group, or cyano group.

(5) Method of Contact

The method for bringing coordination structure-containing compounds intocontact with the surface of a curable resin composition layer is notparticularly limited. Examples include (1) a dipping process in which acoordination structure-containing compound is dissolved in water or anorganic solvent to prepare a solution, and an inner layer board with aresin composition layer formed thereon is immersed in the solution; and(2) a spray process in which the above described solution is coated byspraying or the like on the surface of a resin composition layer formedon the inner layer board. The operation of the contact may be carriedout once or repeatedly two or more times.

The temperature for the contact maybe optionally selected inconsideration of the boiling point and melting point of the coordinationstructure-containing compound or its solution, operability, productivityand the like, and is generally from 10 to 100° C., preferably from 15 to65° C. The contact time may be optionally selected depending on theamount and solution concentration of the coordinationstructure-containing compound to be attached to the surface of amolding, productivity and the like, and is generally from 0.1 to 360minutes, preferably from 0.1 to 60 minutes.

Then, a process of applying inert gas such as nitrogen, or a process ofdrying in an oven at 30 to 180° C., preferably at 50 to 150° C. for oneminute, preferably for 5 to 120 minutes may be carried out for thepurpose of removing the excess coordination structure-containingcompound. When a conductor circuit is made of a metal such as copper,the drying in an oven may be carried out under nitrogen atmosphere interms of preventing oxidation. Moreover, the surface of the board may becleaned by water or an organic solvent prior to these removaloperations.

Coordination structure-containing compounds are dissolved for use insolvents as necessary. Solvents to be used are not particularly limited,and may be selected such that curable resin composition layers are noteasily dissolved in the solvents, and coordination structure-containingcompounds can be dissolved therein. Examples of the solvents includepolar solvents such as water; ethers such as tetrahydrofuran; alcoholssuch as ethanol and isopropanol; ketones such as acetone; cellosolvessuch as ethyl cellosolve acetate; and mixtures thereof. Theconcentration of the coordination structure-containing compound in asolution of the coordination structure-containing compound is, but notlimited to, generally from 0.001 to 70% by weight, preferably from 0.01to 50% by weight, in terms of the operability in the present step.

When the coordination structure-containing compound is a liquid in theoperating temperature and there is no problem in the operation forbringing the coordination structure-containing compound into contactwith the surface of the curable resin composition layer formed in thestep 1, it may be used as it is without dissolving in a solvent.

The solution of the coordination structure-containing compound in thepresent invention is mainly composed of the above described coordinationstructure-containing compound, and the components other than thecoordination structure-containing compound include a surfactant which isused for improving the wetting between the inner layer board with amolding overlapped thereon and the solution of the coordinationstructure-containing compound, and other additives. The amount of use ofthese additives is 10% by weight or less, preferably 5% by weight orless, more preferably 1% by weight or less, relative to the coordinationstructure-containing compound, in terms of ensuring adhesion.

FIG. 3 shows a sectional view of an embodiment in which an inner layerboard with conductor circuits formed on both sides is used; curableresin composition layers 3 and 3′ are formed on both sides thereof; andthen compounds 4 and 4′ having a structure capable of coordinating tometal atoms or metal ions are brought into contact with the top of them.Although FIG. 3 shows that the coordination structure-containingcompounds 4 and 4′ form layers, in reality, excess solution is removedand dried, so that instead of forming a physically separated layer,these compounds are finally adsorbed or penetrated around the surface ofthe curable resin composition layer (mainly penetrated).

The compound having a structure capable of coordinating to metal atomsor metal ions has the effect for improving adhesion even by a smallamount. The amount that is penetrated into the curable resin compositionlayer is preferably from 0.1 μg/m² to 1 g/m², more preferably from 10μg/m² to 500 mg/m².

4. Step 3

Following the step 2, the curable resin composition layer is cured toform the electrical insulating layer (b). The curing of the curableresin composition layer is typically carried out by heating the resincomposition layer (in reality, the whole inner layer board on which theresin composition layer is formed). Curing conditions are appropriatelyselected depending on the type of curing agents. The temperature forcuring is generally from 30 to 400° C., preferably from 70 to 300° C.,more preferably from 100 to 200° C. The time for curing is generallyfrom 0.1 to 5 hours, preferably from 0.5 to 3 hours. The method forheating is not limited, and may be carried out, for example, by using anoven or the like. Typically, for forming multilayer circuit boards,openings for forming via holes are formed in the electrical insulatinglayer (b) prior to forming a metallic thin film layer in order toconnect the conductor circuit (A) of an inner layer board to theconductor circuit (B) to be formed later.

When the openings for forming via holes are formed by photolithography,resists are photo-cured by the masking for forming patterns prior tocuring the curable resin composition layer, and then the part that isnot cured by light is removed before the above described curing iscarried out.

When a process by photolithography is not adopted as the method forforming openings for forming via holes in an electrical insulating layer(b), typically, a resin composition layer is cured to form theelectrical insulating layer (b), and then openings for forming via holesare formed by physical treatment such as drilling, laser and plasmaetching or the like prior to the next step 4. The method using lasersuch as carbon dioxide gas laser, excimer laser or UV-YAG laser ispreferred, in that it can form finer via holes without reducing theproperties of the electrical insulating layer (b).

FIG. 4 shows the state that when a curable resin composition layer iscured, coordination structure-containing compounds 5 and 5′ arepenetrated around the surface of outer layers. In addition, FIG. 4 showsan example that via holes 6 and 6′ are opened.

5. Step 4

The electrical insulating layer (b) for use in step 4 typically hasopenings 6 and 6′ for forming via holes. In step 4, the electricalinsulating layer (b) is formed, and then a metallic thin film layer isformed thereon.

Metallic thin film layers 7 and 7′ may be formed on the surface of theelectrical insulating layer (b) and on the inner wall surface of theopenings 6 and 6′ for forming via holes by electroless plating,sputtering, vacuum deposition or the like. The method for formingmetallic thin film layers is preferably by electroless plating ofsputtering.

When a metallic thin film layer is formed by electroless plating, acatalyst core such as silver, palladium, zinc or cobalt is generallyadsorbed on an electrical insulating layer prior to forming the metallicthin film layer on the electrical insulating layer (b).

The methods for attaching the catalyst core to the electrical insulatinglayer (b) include, but not limited to, for example, a method in whichthe electrical insulating layer (b) is brought into contact with anaqueous alkaline solution such as an aqueous potassium permanganatesolution or an aqueous sodium permanganate solution as necessary;subjected to neutralization and reduction by an aqueous acidic solutionsuch as a mixed solution of hydroxyamine sulfate and sulfuric acid orthe like; and then immersed in a liquid in which a metallic compound ofsilver, palladium, zinc, cobalt or the like, or salts or complexesthereof is dissolved in water or in an organic solvent such as alcoholor chloroform in a concentration of 0.001 to 10% by weight (may containacid, alkali, a complexing agent, reducing agent or the like, asnecessary) to reduce metal.

When the electrical insulating layer (b) is formed using a curable resincomposition containing an insulating polymer having a weight averagemolecular weight of 10,000 to 1,000,000, the roughing in the catalystadsorption treatment prior to forming a metallic thin film layer ishighly suppressed, and the electrical insulating layer (b) issubstantially not roughened. Here, “substantially not roughened” meansthat the electrical insulating layer (b) on which the catalyst isadsorbed has a surface roughness Ra in the range from 0.1 nm to 500 nm,preferably from 0.1 nm to 200 nm.

Any of the known autocatalytic electroless plating solution may be usedas the electroless plating solution for use in electroless plating. Forexample, the electroless plating solutions that can be used include anelectroless copper plating solution using ammonium hypophosphite orhypophosphorous acid, ammonium borohydride or hydrazine, or formaldehydeas a reducing agent; an electroless nickel-phosphorus plating solutionusing sodium hypophosphite as a reducing agent; an electrolessnickel-boron plating solution using dimethylamine borane as a reducingagent; an electroless palladium plating solution; an electrolesspalladium-phosphorus plating solution using sodium hypophosphite as areducing agent; an electroless gold plating solution; an electrolesssilver plating solution; an electroless nickel-cobalt-phosphorus platingsolution using sodium hypophosphite as a reducing agent.

After forming the metallic thin film layer, the surface thereof may bebrought into contact with an anti-corrosive agent to undergoanti-corrosive treatment.

For forming the metallic thin film layer by sputtering, plasma treatmentin which the surface of the electrical insulating layer (b) is broughtinto contact with plasma in advance is preferably performed in order toimprove adhesion. Neon gas, argon gas, krypton gas, xenon gas, nitrogengas or the like is used as the inert gas for use in the plasmatreatment. Among them, nitrogen gas and/or argon gas is preferred. Themethods for generating plasma are not particularly limited, and theinert gas may be introduced into a plasma generating apparatus togenerate plasma.

The methods of plasma treatment are not particularly limited, and may becarried out by using a plasma treatment apparatus generally adopted forforming a conductor circuit comprised of metal on an electricalinsulating layer. The time required for plasma treatment is, but notlimited to, generally from 1 second to 30 minutes, preferably from 10seconds to 10 minutes. The frequency and output of plasma during theplasma treatment, the gas pressure for generating plasma and thetreatment temperature are also not particularly limited, and may be inthe range that can be handled in the plasma treatment apparatus. Thefrequency is typically 13.56 MHz. The output is typically from 50 W to1,000 W. The gas pressure is typically from 0.01 Pa to 10 Pa. Thetemperature is typically from 20° C. to 250° C., preferably from 20° C.to 180° C. If the output is too high, the surface of the electricalinsulating layer may be cracked. If the gas pressure is too high, thesurface smoothness of the electrical insulating layer may be reduced.

The methods of sputtering to be used may include, but not limited to,direct current two-pole sputtering, high frequency sputtering, magnetronsputtering, facing target sputtering, ECR sputtering, bias sputtering,plasma control sputtering, and multi target sputtering. Among them,direct current two-pole sputtering and high frequency sputtering aresuitable. The output for sputtering treatment and gas pressure andtreatment temperature for generating plasma are not particularlylimited, and may be within the range that can be handled by sputteringapparatuses. The output is typically from 10 W to 1,000 W. The gaspressure is typically from 0.01 Pa to 10 Pa. The temperature istypically from 20° C. to 250° C., preferably from 20° C. to 180° C. Therate of film-forming is typically from 0.01 nm/second to 100 nm/second,preferably from 0.1 nm to 10 nm/second. If the film-forming rate is toohigh, the metallic film formed may be cracked. If the gas pressure istoo high, the adhesion may be reduced.

The metallic thin film layer to be formed by the above describedsputtering processes may be formed of one type of metal or a pluralityof metals. The metallic thin film layer may be one layer or formed bylaminating two or more layers. The metals for forming the metallic thinfilm layer may be any metal such as aluminum, iron, tungsten,molybdenum, tin, nickel, chromium, cobalt, manganese, titanium, copper,silver, gold or platinum.

Preferably another metal than copper, more preferably nickel, chromium,cobalt, manganese, molybdenum, tin, or mixtures thereof is formed on thesurface of the electrical insulating layer (b) as the first metallicthin film layer, in that it can obtain excellent adhesion to theelectrical insulating layer (b). Most preferably, the second metallicthin film layer comprised of copper is formed on the first metallic thinfilm layer.

In the present invention, after the metallic thin film layer is formedin step 4 and before step 5, the metallic thin film layer may be heattreated for improving adhesion and the like. The heat treatment may becarried out under pressure.

When the heat treatment is carried out under pressure, the methods forapplying pressure include, for example, the use of a heated pressmachine or a heated press roll machine to physically apply pressure tothe board. The pressure to be applied is typically from 0.1 MPa to 20MPa, preferably from 0.5 MPa to 10 MPa. The heating temperature istypically from 50 to 350° C., preferably from 80 to 250° C. In theseranges, high adhesion can be ensured between the metallic thin filmlayer and the electrical insulating layer (b).

The thickness of the metallic thin film layer is preferably from 10 nmto 3 μm, more preferably from 15 nm to 1 μm. When the thickness iswithin these ranges, the metallic thin film layer may be a single layeror multiple layers. When a copper layer is the top layer and a metallayer other than copper is an intermediate metal layer (primary metallayer), the thickness of the intermediate metal layer is preferably from10 to 500 nm, more preferably from 15 to 300 nm.

FIG. 5 shows a sectional view of the embodiment in which the metallicthin film layers 8 and 8′ are formed on the electrical insulating layers(b, b′) 7 and 7′, respectively, on both sides of the inner layer board.

6. Step 5

In step 5, the metallic thin film layer formed in step 4 is utilized toform the conductor circuit (B) on the surface of the electricalinsulating layer (b).

Various well known processes in the art or publicly known processes suchas a subtractive process, a fully-additive process, and a semi-additiveprocess can be adopted as the method for forming a conductor circuit(conductor pattern) utilizing a metallic thin film layer. Electrolyticplating is generally carried out as a process for forming a metalthickness required for a conductor circuit on a metallic thin film, buta process in which electroless plating is continued may be adopted insome cases.

A method for using electrolytic plating comprises forming resistpatterns on the surface of a metallic thin film layer, performingelectrolytic plating to form an electroplated metal layer in a patternform on the surface of the metallic thin film layer, and then removingthe resist and subjecting to etching, in turn, to form the conductorcircuit (B) on the surface of the electrical insulating layer (b). Theconductor circuit (B) formed by this method is generally comprised of ametallic thin film layer and an electroplated metal layer grown thereon.

FIG. 6 is a sectional view of the embodiment of a multilayer circuitboard comprising conductor circuits (B, B′) 9 and 9′ formed on bothsides of the inner layer board by the above described method.

Other than the above described method, for example, there is a method inwhich a coordination structure-containing compound is brought intocontact with the surface of a curable resin composition layer in apattern form, and the pattern of the compound is utilized to form aconductor circuit by plating. In this case, the coordinationstructure-containing compound that is brought into contact with thesurface of the curable resin composition layer in a pattern form becomesan initiator pattern, and a metallic pattern can be formed byelectroless plating.

Specifically, a conductor circuit (B) is formed on the surface of theelectrical insulating layer (b) by i) bringing a compound having astructure capable of coordination into contact with the surface of thecurable resin composition layer in a pattern form in step 2, ii)performing electroless plating to deposit metal on the pattern of acompound having a structure capable of coordination on the surface ofthe electrical insulating layer (b) to form a metallic thin film layerin a pattern form, in step 4, and iii) further performing electrolessplating on the metallic thin film layer in a pattern form to increasethe thickness of a metal layer, or performing electrolytic plating toform an electroplated metal layer on the pattern of the metallic thinfilm layer, in step 5. When the pattern is fine, the metal layer ispreferably formed only by electroless plating that can provide highpattern accuracy. When the pattern is large, the metal layer ispreferably formed by electrolytic plating after forming the metallicthin film layer, in terms of production efficiency.

In this method, it is preferred in terms of adhesion to add the stepsfor curing a curable resin composition layer to form the electricalinsulating layer (b) and then oxidizing the surface of the electricalinsulating layer (b), in step 3.

Other than these methods, there is, for example, a method for depositingmetal by electrolytic plating or electroless plating on the wholesurface of a metallic thin film layer and then performing etching usingphotolithography technology, remaining the part to be used for acircuit.

7. Other Aspects of Making Multilayers

Above described technologies for making multilayers can be applied notonly on one side of an inner layer board but also on both sides thereof.That is, an inner layer board having the electrical insulating layer (a)with conductor circuit layers (A, A′) formed on both sides thereof canbe used to form the electrical insulating layer (b′) and the conductorcircuit (B′) thereon, also on the other side of the inner layer board soas to cover the conductor circuit layer (A′), by the same steps as step1 through step 5. FIG. 6 shows a sectional view of an example thereof.

In addition, by repeating the same steps as step 1 through step 5 asdesired, two or more layers comprised of a combination of an electricalinsulating layer and a conductor circuit can be formed on either oneside or both sides of the inner layer board. The upper limit in makingmultilayers can be appropriately defined as desired, and includes 5layers or more, 10 layers or more, 50 layers or more, and 70 layers ormore.

8. Applications of Multilayer Circuit Board

The multilayer circuit board obtained by the method of the presentinvention can be used, for example, in electronic equipment such ascomputers and cellular phones, as a printed wiring board for mountingsemiconductor elements such as CPUs and memory, and other mountingcomponents. In particular, those having microscopic wiring are suitable,as high density printed wiring boards, for the wiring boards for highspeed computers and portable terminals for use in the high frequencyrange. Each of the layers may have the same thickness or differentthicknesses.

9. Resin Base Material on which Metallic Patterns are Formed

The compound having a structure capable of coordinating to metal atomsor metal ions (coordination structure-containing compound) is adsorbedto a curable resin composition layer and acts as a plating-inducingsubstance. Therefore, the technology for forming a metallic thin filmlayer using this compound can be applied to a method for formingmetallic patterns by electroless plating on the resin base materialformed from the curable resin composition.

Specifically, the method for manufacturing a resin base material onwhich metallic patterns are formed comprises the steps of: (I) bringinga compound having a structure capable of coordinating to metal atoms ormetal ions into contact with the surface of a resin base material formedfrom a curable resin composition containing an insulating resin and acuring agent in a pattern form; (II) curing the resin base material; and(III) performing electroless plating to deposit metal on the patterns ofa compound having a structure capable of coordination on the surface ofthe resin base material. As for each of the components and materials tobe used, those above described can be used.

(1) Resin Base Material:

The shapes of the resin base material may include, but not limited to, afilm (sheet), a plate, a cylinder or a sphere. The surface state of theresin base material is not particularly limited, and the surface of theresin base material may be irregular or flat as a whole, as long as thepart of the surface in contact with the coordinationstructure-containing compound to be used as a plating inducing substanceis flat in the contact range.

The method for molding a curable resin composition on the resin basematerial is optionally selected depending on the shape of the resin basematerial. For example, each of the components composing the curableresin composition is mixed with an organic solvent to obtain varnish. Itis coated on a support in a desired thickness and the organic solvent isremoved and dried to obtain an uncured or a semi-cured resin basematerial (molding). In the subsequent step, the support is detached fromthe resin base material as necessary.

The organic solvent for obtaining the varnish may be optionally selecteddepending on curable resin compositions, and those having a boilingpoint at atmospheric pressures of generally from 80 to 250° C.,preferably from 90 to 200° C. are selected in terms of the balance ofmoldability and productivity. Similar methods as the above describedmethod for producing films can be adopted as the method for preparingthe varnish and the method for coating the varnish on the support. Theconditions for removing and drying the organic solvent after coating thevarnish on the support is not particularly limited, but for obtaining aresin base material of a thermoplastic resin composition, the conditionsin which it is not completely cured need to be adopted. The conditionsare optionally determined in consideration of the types of insulatingresins and curing agents and the shape of moldings, and for obtaining aresin base material having a thickness of 0.1 to 150 μm, the organicsolvent is generally dried and removed under a heating condition of 20to 300° C. for 30 seconds to one hour.

(2) Adhering Method:

A preferred method of forming an initiator pattern includes a method fordirectly adhering a coordination structure-containing compound on thesurface of a resin base material in a pattern form. Examples of adheringmethods include known adhering methods such as an ink jet system forspraying liquid, a screen printing system for printing via a mask, and adispenser coating system for directly coating liquid. The adheringoperation may be performed once or repeated two or more times.

For adhering, a coordination structure-containing compound is generallydissolved in water or in an organic solvent to be used as a solvent.However, when the compound is in a liquid state at a use temperature andthere is no problem in the operation for adhering it in itself on thesurface of a resin base material, it may be used as it is without beingdissolved in a solvent. As long as the solvent for dissolving thecoordination structure-containing compound does not dissolve the resinmaterial and dissolves the coordination structure-containing compound,it is not particularly limited and may be selected from water or variousorganic solvents which are suitable for the adhering method.

For example, in the ink jet system and screen printing system, polarsolvents having a low volatility or solvents having a high (90° C. orhigher) boiling point is preferably used for ensuring the work abilityin repeated operations. The concentration of the coordinationstructure-containing compound in a coordination structure-containingcompound solution is not particularly limited, and is generally from0.001 to 70% by weight, preferably from 0.01 to 50% by weight in termsof operability in the present step.

In addition, in order to obtain the viscosity depending on adheringmethods, thickeners such as Aerosil or the like may be added for thepurpose of imparting thixotropy to the coordination structure-containingcompound or its solution.

The temperature in the adhering method may be optionally selected inconsideration of the boiling point and melting point of the coordinationstructure-containing compound and its solution, operability, workabilityand the like, and is generally from 10 to 100° C., preferably from 15 to65° C.

After the coordination structure-containing compound is adhered to thesurface of the resin base material, post-treatment may be performed forthe purpose of removing excess coordination structure-containingcompound such as washing of the surface of the resin base material,blowing inert gas such as nitrogen or drying in an oven at 30 to 180°C., preferably at 50 to 150° C. for one minute or more, preferably for 5to 120 minutes.

The coordination structure-containing compound penetrates around thesurface of the resin base material to serve to enhance the interfaceadhesion between the resin base material and the electroless platinglayer.

(3) Curing of the Resin Base Material:

For curing the resin base material, similar conditions as adopted forthe above described method for producing multilayer circuit boards canbe adopted.

By curing, the resin base material is completely cured to form a resinbase material having an initiator pattern on the surface. Conventionalmethod is extremely different from the present invention, in that aplating-inducing substance has been coated on the completely cured resinbase material to form the initiator pattern.

By curing the resin base material after the initiator pattern is formedon the surface of the resin base material which is not completely cured,the coordination structure-containing compound to be a plating-inducingsubstance is incorporated into the surface of the resin base materialand the compound is firmly bonded with the resin base material,resulting in enhanced adhesion with the plating to be formed on theresin base material.

According to the method of the present invention, it is unnecessary toform the initiator pattern after the resin base material surface isroughened, and a resin base material having a flat interface to ametallic pattern can be obtained. Here, the flatness refers to a surfaceroughness Ra of 200 nm or less, preferably 100 nm or less, morepreferably 80 nm or less. The surface roughness Ra is the valuecalculated according to the requirements of JIS B-0601.

(4) Oxidation Treatment:

The use of the coordination structure-containing compound can enhancethe crosslinking density of the surface of the resin base materialduring curing. Consequently, a step for oxidizing the surface of theresin base material, as necessary, can suppress the roughness of theresin base material that is produced at its surface or at the interfacewith the initiator pattern of the resin base material.

In the curing in this step (II), a brittle layer may be formed on thesurface of the resin base material or a contaminant may be adhered to itfrom a curing atmosphere. So it is preferred to subject the surface ofthe base material to oxidizing treatment for the purpose of removingthem. The method for oxidizing the surface of the base material is notparticularly limited, and a method for bringing chemical substances intocontact with the surface of the base material, such as a method forusing a solution of an oxidizing compound or a method for using a gasmedium, is desirable, in that these methods do not roughen the surfaceof the base material.

Known oxidizing compounds having oxidation capability such as inorganicperoxides or organic peroxides can be used as an oxidizing compound. Theinorganic peroxides include permanganates, chromic anhydrides,dichromates, chromates, persulfates, activated manganese dioxide, osmiumtetroxide, hydrogen peroxide, periodates, and ozone. The organicperoxides include dicumylperoxide, octanoyl peroxide, m-chloroperbenzoicacid, and peracetic acid.

The methods for oxidizing the surface of the resin base material usingan oxidizing compound is not particularly limited, and include generalmethods such as, for example, a method in which an oxidizing compound isdissolved in a medium that can dissolve it to form a solution, asnecessary, and then the solution is brought into contact with the resinbase material after cured. Examples of the medium to be used fordissolving the oxidizing compound include a neutral water, an aqueousalkaline solution such as aqueous NaOH solution, an aqueous acidicsolution such as aqueous sulfuric acid solution, a neutral organicsolvent such as ether or petroleum ether, a polar organic solvent suchas acetone or methanol.

The method for bringing the oxidizing compound into contact with thesurface of the resin base material is not particularly limited, andmaybe any method such as, for example, a dipping process for immersingthe resin base material in a solution of the oxidizing compound, aliquid-laying process in which a solution of the oxidizing compound islaid on the surface of the resin base material using surface tension, aspray process for spraying a solution of the oxidizing compound to theresin base material.

The temperature and time for bringing these oxidizing compounds intocontact with the surface of the resin base material may be optionallyset in consideration of the concentration and type of peroxides, contactmethods and the like. The treatment temperature is generally from 20 to250° C., preferably from 20 to 180° C. The treatment time is generallyfrom 0.5 to 60 minutes, preferably from one minute to 30 minutes. In theranges lower than the lower limits of these ranges, removal of thebrittle layer on the surface of the resin base material produced bycuring and the contaminants adhered from a curing atmosphere, aftercuring, is insufficient. In the ranges higher than the higher limits ofthese ranges, the surface of the resin base material may be brittle, orthe smoothness of the surface may be impaired.

After the oxidizing compound is brought into contact with the surface ofthe resin base material, the resin base material is generally washedwith water for removing the oxidizing compound. When the substance thatcannot be washed only by water is adhered to the base material, thesubstance may be further cleaned with a cleaning solution that candissolve the substance, or the substance may be brought into contactwith other compounds to form a water-soluble substance for washing withwater. For example, when an aqueous alkaline solution such as apotassium permanganate solution or a sodium permanganate solution isbrought into contact with a resin base material, neutralization andreduction is performed by an acidic solution such as a mixed solution ofhydroxyamine sulfate and sulfuric acid for the purpose of removing theformed coating film of manganese dioxide.

The methods of oxidization treatment using a gas medium include knownplasma treatment capable of radicalizing or ionizing the medium, such asreverse sputtering or corona discharge. Examples of the gas mediuminclude air, oxygen, nitrogen, argon, water, carbon disulfide, andcarbon tetrachloride. When the medium is liquid in a treatmenttemperature atmosphere, the oxidation treatment is performed after themedium is vaporized under reduced pressure. When the medium is vapor ina treatment temperature atmosphere, the oxidation treatment is performedafter the medium is pressurized to the pressure where radicalization orionization is possible. The temperature and time for bringing plasmainto contact with the surface of the resin base material may beoptionally set in consideration of the type and the flow rate of thegas. The treatment temperature in this case is generally from 10 to 250°C., preferably from 20 to 180° C., and the treatment time is generallyfrom 0.5 to 60 minutes, preferably from one minute to 30 minutes.

(5) Electroless Plating:

In step (III), electroless plating is performed on the initiator patternon the resin base material obtained through step (II).

The electroless plating can be performed under the similar conditions asthose for the above described method of producing multilayer circuitboards. Generally, such treatment as attaching a plating catalyst oractivation of the catalyst is performed prior to the electrolessplating. The plating catalyst is a metallic compound that serves as areducing catalyst for depositing the plating in an electroless platingsolution. The metal includes Pd, Pt, Au, Ag, Ir, Os, Ru, Sn, Zn and Co.Organometallic complexes or metal salts capable of producing metals byreduction are preferably used as the metallic compound in order toenhance the adhesion, and specifically include Pd-amine complexes,palladium sulfate and palladium chloride. The above described methodscan be adopted as the method for attaching the catalyst and activatingit.

Although more catalyst is adsorbed on the initiator pattern (the patternof a coordination structure-containing compound), it is desired that thecatalyst adsorbed to the part without the initiator pattern is removed.Generally, the unnecessary catalyst is removed by washing with waterafter attaching the catalyst or after activating the catalyst.

Thus, the activated catalyst is attached on the initiator pattern of theresin base material and then brought into contact with an electrolessplating solution to perform electroless plating.

The electroless plating solution for use in the electroless plating isnot particularly limited, and those described above can be preferablyused. In addition, after the electroless plating, the surface of theresin base material can also be brought into contact with ananti-corrosive agent to be subjected to anti-corrosive treatment.

After the metallic pattern is formed on the surface of the resin basematerial by performing electroless plating, the resin base material ispreferably heat treated using an oven or the like at 50 to 350° C.,preferably at 80 to 250° C. for 0.1 to 10 hours, preferably for 0.1 to 5hours in order to improve adhesion. At this time, it is preferable toheat it under an inert gas atmosphere such as nitrogen or argon.Further, the resin base material may be pressurized by a press plate orthe like during the heating as necessary.

Through the above described steps, the surface of the resin basematerial is applied with the electroless plating to obtain the resinbase material of the present invention having the metallic patterns onthe surface. This resin base material can be used as the printed wiringboard and the like for use, for example, in semiconductor devicemounting components, various panel display devices, IC cards and opticaldevices.

10. Resin Base Material on which a Metallic Thin Film is Formed

A resin base material on which a metallic thin film is formed can beobtained by the similar method as the method for producing multilayercircuit boards and the method for producing resin base materials onwhich metallic patterns are formed, as described above.

Specifically, the method for producing a resin base material on which ametallic thin film is formed comprises the steps of: (i) bringing acompound having a structure capable of coordinating to metal atoms ormetal ions into contact with the surface of a resin base material formedfrom a curable resin composition containing an insulating resin and acuring agent; (ii) curing the resin base material; and (iii) performingelectroless plating or sputtering to form a metallic thin film on thesurface of the resin base material.

EXAMPLES

The present invention will now be specifically described with referenceto examples and comparative examples. Note that “part” and “%” in theexamples are based on weight unless otherwise specified.

The evaluation methods performed in the present invention are asfollows.

(1) Molecular Weight [Weight Average Molecular Weight (Mw), NumberAverage Molecular Weight (Mn)]:

The molecular weight was measured as a value in terms of polystyrene bygel permeation chromatography (GPC) using toluene as a solvent.

(2) Hydrogenation Ratio and Maleic Acid (Anhydride) Residue Content:

The ratio of hydrogenation to the number of moles of unsaturated bondsin a polymer before hydrogenation (hydrogenation ratio) and the ratio ofthe number of moles of maleic acid (anhydride) to the total monomerunits in the polymer (carboxyl group content) were measured by ¹H-NMRspectroscopy.

(3) Glass Transition Temperature (Tg):

Glass transition temperature (Tg) was measured by differential scanningcalorimetry (DSC).

(4) Roughness of the Resin Surface:

Surface roughness Ra was measured and evaluated by an atomic forcemicroscope (Nanoscope 3a, made by Digital Instrument) using a Si singlecrystal strip cantilever (spring constant=20 N/m, length 125 μm) in atapping mode in air.

(5) Evaluation of a Deposition State of Plating:

The appearance of a substrate of 10 cm square was visually observedafter electroless plating. The deposition of plating that was uniformacross the substrate was referred to as “good”, and occurrence ofblisters or peeling, partial deposition, or no deposition was referredto as “poor”.

(6) Evaluation of Pattern Adhesion:

A multilayer circuit board which has a square conductor pattern having aside of 5 cm formed on the outer most layer was left standing in anatmosphere of a temperature of 85° C. and a relative humidity of 85% for30 hours, and then the conductor pattern was cut along the diagonal witha cutter knife having a sharp end. The cut plating layer was visuallyobserved for the peeling and the occurrence of blisters. Those in whichno peeling or blisters were observed were referred to as “good”, andthose in which peeling or blisters were observed were referred to as“poor”.

Incidentally, in Examples 8 and 9, the adhesion was evaluated accordingto the following methods.

A multilayer circuit board having the pattern for evaluating the platingadhesion stipulated in JIS C-5012-8.5 formed on the outer most layerthereof was left standing in an atmosphere having a temperature of 25°C. and a relative humidity of 65% for 24 hours. Then the platingadhesion test was performed according to JIS C-5012-8.5 and the peelingof a plating layer or the occurrence of blisters was visually observed.Those in which no peeling or blisters were observed were referred to as“good”, and those in which peeling or blisters were observed werereferred to as “poor”.

(7) Evaluation of Patterning Characteristics:

One hundred wiring patterns were formed with a wiring width of 30 μm, adistance between wirings of 30 μm and a wiring length of 5 cm, andevaluated as follows: Those in which all of the 100 patterns have noirregularities were referred to as A; those having small irregularitiesin the shape such as blisters but no deficiency such as peeling werereferred to as B; and those having deficiency were referred to as C.

Example 1

1. Formation of a Curable Resin Composition Layer

8-ethyl-tetracyclo[4.4.0.1^(2,5).1^(7,10)]-dodeca-3-ene was subjected toring-opening polymerization, and the resultant ring-opening polymer wassubjected to hydrogenation reaction to obtain a hydrogenated polymerhaving a number average molecular weight (Mn) of 31,200, a weightaverage molecular weight (Mw) of 55,800, and Tg of about 140° C. Thehydrogenation ratio of the obtained polymer was 99% or higher.

One hundred parts of the obtained polymer, 40 parts of maleic anhydrideand 5 parts of dicumyl peroxide were dissolved in 250 parts oft-butylbenzene and were reacted for 6 hours at 140° C. The resultantreaction product solution was added into 1,000 parts of isopropylalcohol to coagulate the reaction product to obtain amaleicacid-modified hydrogenated polymer. The modified hydrogenated polymerwas vacuum dried at 100° C. for 20 hours. The molecular weights of themodified hydrogenated polymer were Mn=33,200 and Mw=68,300, and Tg=170°C. The maleic acid (anhydride) residue content was 25 mol %.

One hundred parts of the above described modified hydrogenated polymer,40 parts of bisphenol A bis(propyleneglycolglycidylether)ether, 5 partsof 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]benzotria zole, and0.1 part of 1-benzyl-2-phenylimidazole were dissolved in a mixed solventconsisting of 215 parts of xylene and 54 parts of cyclopentanone toobtain a varnish.

The varnish was coated on a polyethylene naphthalate film (carrier film)of 300 mm square and 40 μm thick using a die coater and then dried in anitrogen oven at 120° C. for 10 minutes to obtain a dry film with acarrier film having a resin thickness of 35 μm.

On the other hand, 0.1% solution of2-di-n-butylamino-4,6-dimercapto-s-triazine in isopropyl alcohol wasprepared. In this solution, a double-sided copper-clad board (a corematerial which is obtained by impregnating a glass cloth with a varnishcontaining a glass filler and an epoxy resin which does not containhalogen) having a thickness of 0.8 mm, in which an inner layer circuitwas formed which has a wiring width and a distance between wirings of 50μm each and a conductor thickness of 18 μm and is treated withmicro-etching on the surface, was immersed for one minute at 25° C., anddried in a nitrogen-purged oven for 15 minutes at 90° C. to form aprimer layer.

On the above described inner layer board, the dry film with a carrierfilm was bonded together on both sides of the double-sided copper cladboard such that the resin surface faces inside. This was subjected tothermo-compression bonding as a first press using a vacuum laminatorprovided with press plates made of a heat resistant rubber at top andbottom, under a reduced pressure of 200 Pa, at a temperature of 110° C.and a pressure of 0.5 MPa for 60 seconds. Then this was subjected tothermo-compression bonding as a second press using a vacuum laminatorprovided with press plates made of a heat resistant rubber covered withmetallic press plates at top and bottom, under a reduced pressure of 200Pa, at a temperature of 140° C. and a pressure of 1.0 MPa for 60 secondsto laminate the curable resin composition film.

Only the polyethylene naphthalate film, which is a carrier film, waspeeled from the inner layer board on which the curable resin compositionfilm is laminated.

2. Contact Treatment by a Coordination Structure-containing Compound

Then, the inner layer board on which the curable resin composition filmis laminated was immersed in an aqueous solution which was adjusted sothat 1-(2-aminoethyl)-2-methylimidazole is included in 0.1%, for oneminute at 25° C., and then excess solution was removed by an air knife.

3. Curing

Next, the inner layer board was left standing in a nitrogen oven at 170°C. for 60 minutes, allowing the curable resin composition layer (filmlayer) to be cured to form electrical insulating layers on both sides ofthe inner layer board.

In the obtained electrical insulating layer portions of the laminate,via holes having a diameter of 30 μm for interfacial connection wereformed using the third harmonics of UV-YAG laser, obtaining a multilayerboard with via holes.

4. Electroless Plating

The above described multilayer board with via holes was immersed in anaqueous solution of 80° C. for 15 minutes which was adjusted so as tohave a concentration of permanganic acid of 60 g/liter and aconcentration of sodium hydroxide of 28 g/liter. Then, the board wasimmersed in a water bath for one minute, and further immersed in anotherwater bath for one minute to wash the board with water. Subsequently,the board was immersed in an aqueous solution of 25° C. for 5 minuteswhich was adjusted so as to have a concentration of hydroxylaminesulfate of 170 g/liter and a concentration of sulfuric acid of 80g/liter, being subjected to neutralization and reduction treatment, andthen washed with water, and the water was removed by blowing nitrogen.

The multilayer board after water washing was immersed in a Pdsalt-containing plating catalyst solution of 60° C. for 5 minutes whichwas adjusted to contain 200 ml/liter of ACTIVATOR MAT-1-A (made byUyemura & Co., Ltd.), 30 ml/liter of ACTIVATORMAT-1-B (made by Uyemura &Co., Ltd.), and 1 g/liter of sodium hydroxide. Then, the board waswashed with water according to the same procedures as described above,and immersed in a solution at 35° C. for 5 minutes which was adjusted tocontain 18 ml/liter of REDUCER MRD-2-A (made by Uyemura & Co., Ltd.) and60 ml/liter of REDUCER MRD-2-C (made by Uyemura & Co., Ltd.), subjectingthe plating catalyst to reduction treatment. The surface of the outermost insulating layer of the multilayer board on which the platingcatalyst was adsorbed was evaluated for the roughness in this way, andRa was found to be 63 nm.

The thus obtained multilayer board was immersed to perform theelectroless plating for 15 minutes while blowing air in an electrolessplating solution of 36° C. which was adjusted to contain 100 ml/liter ofPEA-6-A (made by Uyemura & Co., Ltd.), 100 ml/liter of PEA-6-B (made byUyemura & Co., Ltd.), 14ml/liter of PEA-6-C (made by Uyemura & Co.,Ltd.), 12 ml/liter of PEA-6-D (made by Uyemura & Co., Ltd.), 50 ml/literof PEA-6-E (made by Uyemura & Co., Ltd.), and 5 ml/liter of 37% formaldehyde aqueous solution. The multilayer board on which metallic thinfilm layers are formed by the electroless plating was washed with waterin the same manner as described above.

Then, the multilayer board was immersed in an anti-corrosive solution at25° C. for one minute which was adjusted to contain 10 ml/liter of AT-21(made by Uyemura & Co., Ltd.), washed with water in the same proceduresas described above and then dried, applying anti-corrosive treatment.The deposition state of the electroless plating was evaluated.

5. Heat Treatment

The multilayer board which was applied with the anti-corrosive treatmentwas subjected to heating and pressurizing treatment for 30 minutes byapplying a pressure of 3 MPa at 170° C. using a hot press machine.

6. Formation of a Conductor Circuit by Electrolytic Plating

A commercially available dry film of a photosensitive resist was bondedtogether by thermo-compression bonding on the surface of the multilayercircuit board after the heating and pressurizing treatment. The dry filmwas brought into intimate contact with a mask having a patterncorresponding to that for evaluating adhesion, exposed and developed toobtain a resist pattern. Next, it was immersed in a solution containing100 g/liter of sulfuric acid for one minute at 25° C. to remove theanti-corrosive agent, and the portion on which no resist was formed wasapplied with electrolytic copper plating to form an electrolytic copperplating film having a thickness of 18 μm. Then, the resist pattern wasremoved with a removing liquid, and etching treatment was performedusing a mixed solution of cupric chloride and hydrochloric acid to forma conductor pattern (conductor circuit) comprised of the above describedmetallic thin film layer and electrolytic copper plating film, obtaininga two-layered multilayer circuit board with conductor patterns on bothsides.

The roughness of the surface of the electrical insulating layer in theportion without patterns of the obtained multilayer circuit board wasevaluated, and Ra was found to be 78 nm. Moreover, no blisters orpeeling was observed in the patterns on the board. The pattern adhesionand patterning characteristics of the thus obtained multilayer circuitboard were evaluated. The results are shown in Table 1.

Example 2

The experiments were performed in the same manner as in Example 1,except that 0.1% aqueous solution of2,4,6-trimercapto-s-triazine-monosodium salt was used as a substitutefor 1-(2-aminoethyl)-2-methylimidazole, in the step of contact treatmentby a coordination structure-containing compound in Example 1.

The roughness of the surface of an electrical insulating layer that isthe outer most layer after subjected to the pre-treatment for platingwas evaluated, and Ra was found to be 43 nm. The state of platingdeposition after subjected to electroless plating was evaluated.

The roughness of the surface of the electrical insulating layer in theportion without patterns of the obtained multilayer circuit board wasevaluated, and Ra was found to be 58 nm. Moreover, no blisters orpeeling was observed in the patterns on the board. The pattern adhesionand patterning characteristics of the thus obtained multilayer circuitboard were evaluated. The results are shown in Table 1.

Example 3

A varnish was prepared in the same manner as in Example 1 and amultilayer circuit board was manufactured in the same manner as inExample 1, except that 60 parts of poly(2,6-dimethylphenylene-1,4-ether)(Mw=18,000) and 40 parts of an epoxy resin (trade name: Epicoat 1000:made by Yuka-Shell Epoxy Co., Ltd.: Mw=1,300) were used as a substitutefor 100 parts of the modified hydrogenated polymer used in Example 1.

The roughness of the surface of an electrical insulating layer that isthe outer most layer after subjected to the pre-treatment for platingwas evaluated, and Ra was found to be 82 nm. The state of platingdeposition after subjected to electroless plating was evaluated.

The roughness of the surface of the insulating layer in the portionwithout patterns of the obtained multilayer circuit board was evaluated,and Ra was found to be 96 nm. Moreover, no blisters or peeling wasobserved in the patterns on the board. The pattern adhesion andpatterning characteristics of the thus obtained multilayer circuit boardwere evaluated. The results are shown in Table 1.

Example 4

The treatment was performed in the same manner as in Example 1, exceptthat 0.1% aqueous solution of 3-amino-4-cyanopyrazole was used for thetreatment as a substitute for 1-(2-aminoethyl)-2-methylimidazole, in thestep of contact treatment by a coordination structure-containingcompound in Example 1. The roughness of the surface of an electricalinsulating layer that is the outer most layer after subjected to thepre-treatment for plating was evaluated, and Ra was found to be 57 nm.The state of plating deposition after subjected to electroless platingwas evaluated.

The roughness of the surface of the electrical insulating layer in theportion without patterns of the obtained multilayer circuit board wasevaluated, and Ra was found to be 62 nm. Moreover, no blisters orpeeling was observed in the patterns on the board. The pattern adhesionand patterning characteristics of the thus obtained multilayer circuitboard were evaluated. The results are shown in Table 1.

Comparative Example 1

A multilayer circuit board was obtained by the same manner as in Example3, except that the treatment with an aqueous solution of1-(2-aminoethyl)-2-methylimidazole in Example 3 was eliminated.

The roughness of the surface of the electrical insulating layer in theportion without patterns of the obtained multilayer circuit board wasevaluated, and Ra was found to be 21 nm. Moreover, numbers of blistersand peeling having a width of 5 mm or less were observed in the patternson the board, and further blisters and peeling having a width largerthan 5 mm were observed. The results are shown in Table 1.

TABLE 1 Plating deposition Pattern Patterning Examples state adhesioncharacteristics Example 1 good good A Example 2 good good A Example 3good good A Example 4 good good A Comparative poor poor C example 1

Example 5

The obtained varnish in Example 1 was not coated on a carrier film, butwas directly coated on the inner layer board having a primer layerformed thereon using a die coater, and subsequently dried in a nitrogenoven for 10 minutes at 120° C. to form a curable resin composition layerhaving a thickness of 35 μm. A two-layered multilayer circuit board withconductor patterns on both sides was obtained by the same manner as inExample 1, except that it was immersed in an aqueous solution for oneminute at 25° C. which was adjusted to contain 0.1% of1-(2-aminoethyl)-2-methylimidazole.

The roughness of the surface of the electrical insulating layer in theportion without patterns of the obtained multilayer circuit board wasevaluated, and Ra was found to be 85 nm. The state of plating depositionand the evaluation of adhesion of the obtained multilayer circuit boardwere both “good”. As for the evaluation of patterning characteristics,blisters in patterns, which were all 5 mm wide or less, caused by thepoor in-plane uniformity of the adhesion between the electricalinsulating layer and the conductor circuit were observed at threelocations.

Example 6

A multilayer board with via holes was obtained by the same procedures asin Example 1. The surface of this multilayer board was subjected toplasma treatment. The conditions of the plasma treatment were asfollows: the type of the gas was argon; the conditions of the plasmatreatment apparatus included a frequency of 13.56 MHz, an output of 100W, and a gas pressure of 0.8 Pa; the temperature during treatment was25° C.; and the time for treatment was 5 minutes. The roughness of thesurface of the electrical insulating layer after the plasma treatmentwas evaluated, and Ra was found to be 50 nm or less.

On the surface of the thus obtained multilayer board which was subjectedto plasma treatment after via holes were formed, a chromium film havinga thickness of 0.03 μm was formed at a rate of 0.46 nm/second by RFsputtering under an argon atmosphere in the conditions of a frequency of13.56 MHz, an output of 400 W and a gas pressure of 0.8 Pa, and then acopper thin film having a thickness of 0.3 μm was formed at a rate of0.91 nm/second.

After the metallic thin film layer was formed on the surface of themultilayer board, a commercially available photosensitive dry film wasbonded to the surface by thermo-compression bonding. The dry film wasbrought into intimate contact with a mask having a predeterminedpattern, exposed and developed to obtain a resist pattern. Next, theelectrolytic copper plating having a thickness of 35 μm was grown on theportions without resist patterns. Then, the surface of the board onwhich the copper plating has grown was brought into contact with areleasing liquid to remove the resist patterns, and the sputtering filmhidden under the portions where the resist has been formed was removedby a mixed solution of cupric chloride and hydrochloric acid to form aconductor pattern. Finally, it was subjected to annealing for 30 minutesat 170° C. to obtain a multilayer circuit board.

The roughness of the surface of the electrical insulating layer in theportion without patterns of the obtained multilayer circuit board wasevaluated, and Ra was found to be 50 nm or less. The pattern adhesionand patterning characteristics of the obtained multilayer circuit boardwere evaluated, and were found to be “good” and “A”, respectively.Further, the peel strength between the electrical insulating layer andthe conductor circuit was determined for the multilayer circuit boardaccording to JIS C-6481, and it was found to be 960 gf/cm.

Example 7

A multilayer circuit board was obtained by the same manner as in Example6, except that the type of gas for plasma treatment was changed tonitrogen. The pattern adhesion and patterning characteristics of themultilayer circuit board were evaluated, and were found to be “good” and“A”, respectively. The result of the evaluation of the peel strength wasfound to be 920 gf/cm. Moreover, the surface roughness Ra both for theelectrical insulating layer after plasma treatment and for theelectrical insulating layer in the portion without patterns of theobtained multilayer circuit board was evaluated, and was found to be 50nm or less for both.

Comparative Example 2

A multilayer circuit board was obtained by the same procedures asExample 5, except that the treatment with an aqueous solution of1-(2-aminoethyl) -2-methylimidazole was eliminated. The surfaceroughness Ra both for the electrical insulating layer after plasmatreatment and for the electrical insulating layer in the portion withoutpatterns of the obtained multilayer circuit board was evaluated, and wasfound to be 50 nm or less for both, and the patterning characteristicswere evaluated as A. However, the pattern adhesion of this multilayercircuit board was poor, and the peel strength was only 650 gf/cm.

From the above results, it can be understood that, when an electricalinsulating layer is formed by using a curable resin compositioncontaining an insulating polymer and a curing agent, the treatment ofthe surface of the curable resin composition layer with a compoundhaving a structure capable of coordinating to metals prior to the curingstep for forming the electrical insulating layer provides stableadhesion at the interface between the electrical insulating layer andthe conductor circuit and provide good pattern adhesion and patterningcharacteristics, without roughening the surface of the electricalinsulating layer (each Example).

Further, it was found that the formation of metallic thin films bysputtering provides high peel strength (Examples 6 and 7).

On the other hand, when the curable resin composition layer is notsurface treated with a compound having a structure capable ofcoordinating to metals, the adhesion between the electrical insulatinglayer without roughing and the conductor circuit is poor and thepatterning characteristics are reduced (Comparative Examples 1 and 2).

Example 8

1. Formation of a Curable Resin Composition Layer

Curable resin composition layers were formed on both sides of adouble-sided copper-clad board in the same manner as in Example 1. Onlythe polyethylene naphthalate film, which is a carrier film, was peeledfrom the inner layer board on which the curable resin composition filmis laminated. The surface roughness of the curable resin compositionlayer was evaluated, and Ra was found to be 14 nm.

2. Adhesion of a Coordination Structure-containing Compound in a PatternForm

Desired wiring patterns were drawn by an aqueous solution which wasprepared to contain 0.3% of 1-(2-aminoethyl)-2-methylimidazole as aplating-inducing substance using an ink jet apparatus on the surfaces ofthe curable resin composition layers laminated on the inner layer board,forming initiator patterns for electroless plating on the surfaces ofthe molding. This was left standing in a nitrogen oven at 170° C. for 60minutes, allowing the curable resin composition layers to be cured toform electrical insulating layers which are resin base materials on theinner layer board, obtaining a laminate. Initiator patterns are formedon the surfaces of the laminate.

In the obtained electrical insulating layer portions of the laminate,via holes having a diameter of 30 μm for interfacial connection wereformed using the third harmonics of UV-YAG laser, obtaining a multilayerboard with via holes.

3. Electroless Plating

As the pre-treatment for plating, the above described multilayer boardwith via holes was immersed under shaking in an aqueous solution of 80°C. for 10 minutes which was adjusted so as to have a concentration ofpermanganic acid of 60 g/liter and a concentration of sodium hydroxideof 28 g/liter to oxidize the surface. Then, the board was immersed undershaking in a water bath for one minute, and further immersed undershaking in another water bath for one minute to wash the board withwater. Subsequently, the board was immersed in an aqueous solution of25° C. for 5 minutes which was adjusted so as to have a concentration ofhydroxylamine sulfate of 170 g/liter and a concentration of sulfuricacid of 80 g/liter, being subjected to neutralization and reductiontreatment, and then washed with water, and the water was removed byblowing nitrogen.

For attaching a plating catalyst, the multilayer board after waterwashing was immersed in a Pd salt-containing plating catalyst solutionof 60° C. for 5 minutes which was adjusted to contain 200 ml/liter ofACTIVATOR MAT-1-A (made by Uyemura & Co., Ltd.), 30 ml/liter ofACTIVATOR MAT-1-B (made by Uyemura & Co., Ltd.), and 1 g/liter of sodiumhydroxide. Then, for activating the catalyst, the board was washed withwater according to the same procedures as described above, and thenimmersed in a solution at 35° C. for 5 minutes which was adjusted tocontain 18 ml/liter of REDUCER MRD-2-A (made by Uyemura & Co., Ltd.) and60 ml/liter of REDUCER MRD-2-C (made by Uyemura & Co., Ltd.), subjectingthe plating catalyst to reduction treatment. The surface of the outermost insulating layer of the obtained multilayer board on which theplating catalyst was adsorbed was evaluated for the roughness in thisway, and the Ra of the portion on which patterns were drawn was found tobe 32 nm, and the Ra of the portion on which patterns were not drawn wasfound to be 29 nm, obtaining about the same Ra values.

The thus obtained multilayer board was immersed to perform theelectroless plating for 15 minutes while blowing air in the electrolessplating solution of 25° C. which was adjusted to contain 150 ml/liter ofTHRU-CUP PRX-1-A(made by Uyemura & Co., Ltd.),100 ml/liter of THRU-CUPPRX-1-B (made by Uyemura & Co., Ltd.), and 20 ml/liter of THRU-CUPPRX-1-C (made by Uyemura & Co., Ltd.). The multilayer board on which themetallic pattern is formed in a desired pattern form was obtained bywashing with water in the same manner as described above.

4. Formation of a Conductor Circuit

For the purpose of increasing the thickness of the metallic pattern onthe multilayer board, it was immersed for 5 hours to perform theelectroless plating while blowing air in the high-speed electrolessplating solution of 60° C. which was adjusted to contain 80 ml/liter ofTHRU-CUP ELC-SP-A (made by Uyemura & Co., Ltd.), 20 ml/liter of THRU-CUPELC-SP-B (made by Uyemura & Co., Ltd.), and 80 ml/liter of THRU-CUPELC-SP-C (made by Uyemura & Co., Ltd.), and 20 ml/liter of THRU-CUPELC-SP-D (made by Uyemura & Co., Ltd.), further overlaying the metal onthe metallic pattern of 18 μm thick formed previously. The multilayerboard on which the metallic pattern is formed in a desired pattern formwas obtained by further washing with water in the same manner asdescribed above. Then, the multilayer board was immersed in ananti-corrosive solution at 25° C. for one minute which was adjusted tocontain 10 ml/liter of AT-21 (made by Uyemura & Co., Ltd.), washed withwater in the same procedures as described above and then dried, applyinganti-corrosive treatment.

5. Heat Treatment

The multilayer board which was applied with the anti-corrosive treatmentwas left standing in an oven of nitrogen atmosphere for 30 minutes at170° C. to subject to heat treatment to obtain a multilayer circuitboard having metallic patterns formed by the electroless copper platingon both sides thereof. The roughness of the surface of the electricalinsulating layer (resin base material) in the portion without patternsof the obtained multilayer circuit board was evaluated, and Ra was foundto be 31 nm. The patterning characteristics and plating adhesion of theobtained multilayer circuit board were evaluated. The results are shownin Table 2.

Example 9

To 100 parts of an aqueous solution which was adjusted to contain 0.3%of 1-(2-aminoethyl)-2-methylimidazole, 15 parts of AEROJIL RY200 (madeby Nippon Aerosil Co., Ltd.) was added for the purpose of impartingthixotropy, and mixed and dispersed at a peripheral speed of 10 m/secondusing a dissolver to prepare a dispersion.

The experiment was performed in the same manner as in Example 8, exceptthat the above described dispersion was used as a substitute for anaqueous solution which was adjusted to contain 0.3% of1-(2-aminoethyl)-2-methylimidazole in Example 8 and the apparatus usedfor drawing the initiator pattern was changed to a screen printer.

The surface of the outer most electrical insulating layer aftersubjected to the pre-treatment for plating was evaluated for theroughness, and the Ra of the portion on which initiator patterns wereprinted was found to be 58 nm, and the Ra of the portion on whichinitiator patterns were not printed was found to be 32 nm, obtainingabout the same Ra values.

The roughness of the surface of the electrical insulating layer in theportion without patterns of the obtained multilayer circuit board wasevaluated, and Ra was found to be 33nm. The pattern adhesion andpatterning characteristics of the obtained multilayer circuit board wereevaluated. The results are shown in Table 2.

TABLE 2 Patterning Examples Adhesion characteristics Example 8 good AExample 9 good A

INDUSTRIAL APPLICABILITY

The present invention provides a method for manufacturing multilayercircuit boards excellent in adhesion of conductor patterns (circuits) toelectrical insulating layers. The present invention further provides amethod for manufacturing resin base materials on which metallic patternsor metallic thin films are formed, suitable for manufacturing multilayercircuit boards and the like.

The multilayer circuit board obtained by the method of the presentinvention can be used, for example, in electronic equipment such ascomputers and cellular phones, as a printed wiring board for mountingsemiconductor elements such as CPUs and memory, and other mountingcomponents. The resin base material obtained by the method of thepresent invention can be used as the printed wiring board and the likefor use, for example, in semiconductor device mounting components,various panel display devices, IC cards and optical devices.

1. A method for manufacturing a multilayer circuit board comprising: 1)step 1 of forming a curable resin composition layer containing aninsulating resin and a curing agent on one or both sides of an innerlayer board having an electrical insulating layer with a conductorcircuit formed on one or both sides thereof, so as to cover saidconductor circuit; 2) step 2 of bringing a compound having a structurecapable of coordinating to metal atoms or metal ions into contact withthe surface of said curable resin composition layer and removing anexcess of said compound from the surface of said curable resincomposition layer after said contact of said compound with the surfaceof said curable resin composition layer, wherein said compound is i) anorganic compound having an amino group, a thiol group, a carboxyl group,or a cyano group, ii) a heterocyclic compound having a nitrogen atom, anoxygen atom, or a sulfur atom, or iii) an imidazole, a pyrazole, atriazole, or a triazine having an amino group, a thiol group, a carboxylgroup, or a cyano group, wherein said compound is penetrated into thesurface of said curable resin composition layer, and wherein the excessof said compound is removed from the surface of said curable resincomposition layer whereby no layer of said compound is formed on thesurface of said curable resin composition layer; 3) step 3 of forming anelectrical insulating layer by curing said curable resin compositionlayer, wherein said compound having a structure capable of coordinatingto metal atoms or metal ions has penetrated into the surface of theelectrical insulating layer and is held within said electricalinsulating layer; 4) step 4 of forming at least one metallic thin filmlayer on the surface of said electrical insulating layer of step 3; and5) step 5 of forming a conductor circuit on the surface of saidelectrical insulating layer of step 3 utilizing said metallic thin filmlayer.
 2. The manufacturing method according to claim 1, wherein saidcurable resin composition layer is formed by bonding a film of a curableresin composition containing an insulating resin and a curing agent tothe one or both sides of said inner layer board so as to cover saidconductor circuit in step
 1. 3. The manufacturing method according toclaim 1, wherein said curable resin composition layer is formed bycoating a solution containing an insulating resin and a curing agent onthe one or both sides of said inner layer board so as to cover saidconductor circuit in step 1 and then drying the solution.
 4. Themanufacturing method according to claim 1, wherein the insulating resinfor use in step 1 is at least one insulating resin selected from thegroup consisting of epoxy resins, maleimide resins, (meth)acrylicresins, diallyl phthalate resins, triazine resins, cycloaliphatic olefinpolymers, aromatic polyether polymers, benzocyclobutene polymers,cyanate ester polymers, liquid crystal polymers and polyimide resins. 5.The manufacturing method according to claim 1, wherein the insulatingresin is an insulating polymer having a weight average molecular weightin the range of 10,000 to 1,000,000.
 6. The manufacturing methodaccording to claim 5, wherein said insulating polymer is acycloaliphatic olefin polymer or an aromatic polyether polymer.
 7. Themanufacturing method according to claim 1, further comprising a step offorming an opening for forming a via hole before or after curing saidcurable resin composition layer in step
 3. 8. The manufacturing methodaccording to claim 1, wherein the metallic thin film layer is formed byelectroless plating in step
 4. 9. The manufacturing method according toclaim 1, wherein the metallic thin film layer is formed by sputtering instep
 4. 10. The manufacturing method according to claim 9, wherein themetallic thin film layer is formed by sputtering after the surface ofthe electrical insulating layer of step 3 is subjected to plasmatreatment.
 11. The manufacturing method according to claim 1, whereinthe metallic thin film layer has a two-layer structure and is formed byforming an intermediate metallic thin film layer consisting of nickel,chromium, cobalt, manganese, molybdenum, tin, or mixtures of two or morethereof on the surface of said electrical insulating layer of step 3,and by further forming a copper thin film layer on said intermediatemetallic thin film layer in step
 4. 12. The manufacturing methodaccording to claim 1, further comprising a step of heat treating themetallic thin film layer after said metallic thin film layer is formedin step
 4. 13. The manufacturing method according to claim 1, whereinthe conductor circuit of step 5 is formed on the surface of saidelectrical insulating layer of step 3 performing electrolytic platingafter forming a resist pattern on said metallic thin film layer to forman electroplated metal layer in a pattern form on the surface of saidmetallic thin film layer, and then removing the resist and subjecting toetching in turn in step
 5. 14. The manufacturing method according toclaim 1, wherein the conductor circuit of step 5 is formed on thesurface of said electrical insulating layer of step 3 by i) bringing thecompound having a structure capable of coordination into contact withthe surface of said curable resin composition layer in a pattern form instep 2; ii) performing electroless plating to deposit metal on thepattern of the compound having a structure capable of coordination onthe surface of said electrical insulating layer to form the metallicthin film layer in a pattern form in step 4; and iii) further performingelectroless plating on the metallic thin film layer in a pattern form toincrease the thickness of the metal layer, or performing electrolyticplating to form an electroplated metal layer on the pattern of saidmetallic thin film layer in step
 5. 15. The manufacturing methodaccording to claim 14, further comprising a step of oxidizing thesurface of the electrical insulating layer of step 3 after said curableresin composition layer is cured to form said electrical insulatinglayer in step
 3. 16. The manufacturing method according to claim 1,wherein at least two layers comprised of a combination of an electricalinsulating layer and a conductor circuit are further formed on eitherone side or both sides of said inner layer board, by repeating the samesteps as step 1 through step
 5. 17. A method for manufacturing a resinbase material on which a metallic pattern is formed comprising: I) stepI of bringing a compound having a structure capable of coordinating tometal atoms or metal ions into contact in a pattern form with one orboth sides of a resin base material formed from a curable resincomposition containing an insulating resin and a curing agent, andremoving an excess of said compound from the one or both sides of theresin base material after said contact of said compound with the one orboth sides of the resin base material, wherein said compound is i) anorganic compound having an amino group, a thiol group, a carboxyl group,or a cyano group, ii) a heterocyclic compound having a nitrogen atom, anoxygen atom, or a sulfur atom, or iii) an imidazole, a pyrazole, atriazole, or a triazine having an amino group, a thiol group, a carboxylgroup, or a cyano group, wherein said compound is penetrated into theone or both sides of the resin base material, and wherein the excess ofsaid compound is removed from the surface of said resin base materialwhereby no layer of said compound is formed on the one or both sides ofthe resin base material; II) step II of curing said resin base materialto form a cured resin base material, wherein the compound having astructure capable of coordinating to metal atoms or metal ions haspenetrated into the cured resin base material and is held within thecured resin base material; and III) step III of performing electrolessplating to deposit metal on the pattern of the compound having astructure capable of coordination on the surface of said cured resinbase material.
 18. The manufacturing method according to claim 17,further comprising a step of oxidizing the surface of said cured resinbase material after said resin base material is cured in step II. 19.The manufacturing method according to claim 17, further comprising astep of heat treating said cured resin base material after step III. 20.A method for manufacturing a resin base material on which a metallicthin film is formed comprising: i) step i of bringing a compound havinga structure capable of coordinating to metal atoms or metal ions intocontact with one or both sides of a resin base material formed from acurable resin composition containing an insulating resin and a curingagent, and removing an excess of said compound from the one or bothsides of the resin base material after said contact of said compoundwith the one or both sides of the resin base material, wherein saidcompound is I) an organic compound having an amino group, a thiol group,a carboxyl group, or a cyano group, II) a heterocyclic compound having anitrogen atom, an oxygen atom, or a sulfur atom, or III) an imidazole, apyrazole, a triazole, or a triazine having an amino group, a thiolgroup, a carboxyl group, or a cyano group, wherein said compound ispenetrated into the one or both sides of the resin base material, andwherein the excess of said compound is removed from the surface of saidresin base material whereby no layer of said compound is formed on theone or both sides of the resin base material; ii) step ii of curing saidresin base material to form a cured resin base material, wherein thecompound having a structure capable of coordinating to metal atoms ormetal ions has penetrated into the cured resin base material and is heldwithin the cured resin base material; and iii) step iii of performingelectroless plating or sputtering to form a metallic thin film on thesurface of said cured resin base material.